v0.6.2 - Expanded i18n coverage and Dutch translation polish

[bscott]

Summary

Expands UI translation coverage across the app and merges @callmenoodles's Dutch translation polish (#115).

Closes #115 (Dutch translation improvements — merged into this branch)
Addresses #116 (i18n coverage gaps — covers most surfaces; see below)

What's covered

Calendar

• Month name (now translated server-side via the catalog instead of hardcoded Format("January 2006"))
• Day abbreviations (Sun–Sat)
• Today button
• Export to iCal
• Copy-confirmation toast in the iCal subscribe button

Subscriptions

• Status display (Active / Cancelled / Paused / Trial) via new statusLabel template func
• Schedule display via new scheduleLabel template func (handles both single-interval and "Every N Months" forms)
• These now translate consistently on the dashboard, subscriptions list, and subscriptions table.

Forms

• Payment-method, Account, URL, and Notes placeholders

Settings

• Page subtitle ("Manage your SubTrackr preferences and data")
• Section descriptions: Appearance, Export Data, Base URL, Calendar Subscription, Data Management, Email Notifications, Pushover, Webhook, Security, Currency, Date Format, Categories, API Keys
• SMTP username/to-email placeholders
• Pushover help text snippets
• Webhook URL and headers placeholders
• API key generate button, placeholder, and empty state
• Category creation placeholder

Mobile menu

• "Add Subscription" button (was hardcoded across calendar, dashboard, analytics, settings)

Locale parity

All four locales rebuilt to 282 keys with full parity:

• en.json — canonical
• de.json — German translations added
• es.json — Spanish translations added
• nl.json — includes both the new keys and @callmenoodles's polish (Agenda, Aankomende, herstellink, etc.)

Translations follow the existing AI-assisted convention documented in web/locales/README.md — native speakers welcome to refine.

Code changes

• cmd/server/main.go — new statusLabelFunc, scheduleLabelFunc, monthLabelFunc template funcs registered on both FuncMap sites.
• internal/handlers/subscription.go — Calendar handler now resolves MonthName through the i18n catalog.
• internal/handlers/settings.go — SettingsHandler now receives the i18n catalog and has an activeLang() helper; api-keys-list.html partial gets Lang so its empty state translates.

Deferred from #116

A few items are not in this PR — they need a separate effort:

• Full API documentation translation (Settings → API Documentation section). It's large reference material and standard practice keeps it English; documented as English-by-design in web/locales/README.md.
• Currency display names (every "USD - US Dollar" etc.). Sizable list, low signal-to-noise.
• Locale-aware number formatting ($1,000.00 → $1.000,00). Architectural change touching every cost render path.

Will follow up on these in a separate issue/PR.

Test plan

• go build ./... clean
• go test ./... passes (handlers, i18n, models, service)
• Smoke test: all four pages (calendar, dashboard, settings, subscriptions) return 200 in both English and Dutch
• Verified Dutch calendar renders translated month name, day abbreviations, Today, and Export to iCal
• Manual verification of each settings section in de/es/nl
• Run playwright i18n-coverage spec (npx playwright test tests/i18n-coverage.spec.js --workers=1)

Greptile Summary

This PR expands i18n coverage across the app (calendar day/month names, subscription status and schedule labels, settings section descriptions, form placeholders, mobile menu) and merges Dutch translation polish from a community contributor. All four locale files (en, de, es, nl) are rebuilt to 282 keys with full parity.

• New statusLabelFunc and scheduleLabelFunc Go template funcs translate subscription status/schedule consistently across the dashboard, subscriptions list, and table.
• SettingsHandler now accepts the i18n catalog so the API-keys partial can render its empty state in the active language.
• Dutch locale receives renamed keys (Agenda, Aankomende, herstellink) and a batch of newly added translation keys alongside the rest.

Confidence Score: 5/5

This PR is safe to merge — all changes are additive i18n wiring with no logic mutations, and all four locale files are complete and in parity.

The changes are purely translational: new template functions delegate to the i18n catalog with key-miss fallbacks, existing handler logic is untouched, and the locale files are verified complete. The two findings are edge-case defensive gaps (plural schedule label and printf format string) that are unreachable with the current four locales — they would only surface if a fifth, partially-translated locale were added.

cmd/server/main.go (scheduleLabelFunc plural branch) and templates/settings.html (printf with catalog format string) both lack key-miss guards that the rest of the codebase applies consistently.

Important Files Changed

Filename	Overview
cmd/server/main.go	Adds statusLabelFunc and scheduleLabelFunc template funcs; the plural branch of scheduleLabelFunc calls fmt.Sprintf on the raw catalog return value without checking for a key miss, which can produce garbled output.
internal/handlers/settings.go	SettingsHandler now takes i18nCatalog; activeLang() helper mirrors the existing SubscriptionHandler pattern; Lang field correctly propagated to all api-keys-list.html render paths.
internal/handlers/subscription.go	Calendar handler now resolves month name via i18n catalog with proper key-miss detection (monthName == monthKey fallback).
templates/settings.html	Broad i18n coverage added; uses printf with a catalog-sourced format string for the high-cost threshold label, which produces garbled output on a translation miss.
templates/calendar.html	Day abbreviations, Today button, Export to iCal, and clipboard copy-confirmation toast are now translated; html/template contextual escaping handles the script-block string values safely.
web/locales/en.json	Canonical locale extended with 70+ new keys covering all surfaces touched in this PR; keys are consistent with template usage.
web/locales/nl.json	Dutch translation polished (Agenda, Aankomende, herstellink) and extended to match the new canonical key set.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[HTTP Request] --> B{activeLang}
    B -->|lang setting| C[i18nCatalog.T]
    C -->|hit| D[Translated string]
    C -->|miss: returns key| E[Key string]

    D --> F{Template function}
    E --> F

    F -->|statusLabel| G{v != key?}
    G -->|yes| H[Return translation]
    G -->|no| I[Return raw status]

    F -->|scheduleLabel interval≤1| J{v != key?}
    J -->|yes| K[Return translation]
    J -->|no| L[Return raw schedule]

    F -->|scheduleLabel interval>1| M[fmt.Sprintf catalog.T ...]
    M -->|hit: has %d| N[Return 'Every 3 Months']
    M -->|miss: no %d in key| O[⚠️ Garbled output]

    F -->|monthName in subscription.go| P{monthName == monthKey?}
    P -->|yes fallback| Q[Go Format January]
    P -->|no| R[Return translation]

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_{Reviews (2): Last reviewed commit: "Address Greptile PR #118 review" | Re-trigger Greptile}

[bscott]

Playwright i18n-coverage spec results:

18 passed (15.8s)

All es/de/nl translations render on dashboard, subscriptions, form/subscription, settings, analytics, and calendar pages. No English sentinels leaked through. (Firefox/Webkit projects skipped — browsers not installed locally; chromium covers all assertions.)

[bscott]

Addressed Greptile's review (243f344):

1. Dead fallback in Calendar handler — fixed. catalog.T() returns the key on miss, never "". Now compares against the key string to detect a real miss before falling back to firstOfMonth.Format("January").
2. Unused monthLabelFunc — removed from both FuncMap registrations and its definition. Month translation is server-side in the Calendar handler; no template needed it.
3. printf "%q" JS string injection risk — dropped both printf "%q" pipes. html/template's contextual auto-escape pipeline now produces the JS string literals ("Gekopieerd!", "Abonneren"), which correctly HTML-escapes < > /.

Verified locally:

• go build ./... clean
• Calendar in Dutch renders "Vandaag", "Exporteren naar iCal", day abbrs "Zo Ma Di Wo Do Vr Za", and the JS toast strings as properly-quoted Dutch ("Gekopieerd!", "Abonneren").
• Playwright i18n-coverage spec: 18/18 chromium tests pass.