Add periodic-note formats: week/month/quarter/year granularity

[Amato21]

Summary

Closes #49. Implements the full ("option 2") scope: not just week formats (as proposed in the referenced upstream PR/issue), but week and month and quarter and year, with granularity detection built into the parser rather than a single hardcoded case.

New optional settings (Settings → Periodic notes), each empty/disabled by default:

• weekFormat (e.g. GGGG-[W]WW)
• monthFormat (e.g. YYYY-MM)
• quarterFormat (e.g. YYYY-[Q]Q)
• yearFormat (e.g. YYYY)

When an expression resolves to a whole period instead of a single day — @next week, @this quarter, @Q3, @Q3 2026, @2026-W02 — the corresponding format is used instead of the daily Date format, for linking to Periodic Notes-style weekly/monthly/quarterly/yearly notes. Leaving a field empty keeps existing behavior unchanged, including @next week's current behavior of inserting a link for every day of the week (backward compatible, opt-in).

Implementation

• NLDParser.getParsedPeriod() (new): detects granularity via this/next/last week|month|quarter|year in all 12 languages (both word orders — French postposes the prefix, e.g. "la semaine prochaine") plus language-neutral explicit forms (Q3, Q3 2026, 2026-Q3, 2026-W02). Falls back to the existing getParsedDate() (day granularity) for everything else — the existing day-granularity path is untouched.
• getParsedDateRange() now tags its existing "next week" result with granularity: "week", so getParseCommand() can prefer the single weekFormat value over the existing 7-day link list when configured, without changing that list's default behavior when weekFormat is empty.
• Added a quarter vocabulary entry to all 12 language dictionaries (en/fr/es/it/de/pt/ru/uk/nl/ja/zh/ko).

Bugs found along the way (via empirical per-language verification)

Per this repo's CLAUDE.md rule ("verify empirically per language, not just read the code"), I wrote per-language regression tests for all 12 languages before considering this done — that caught two pre-existing gaps unrelated to the new feature itself:

• French word order: "semaine prochaine" (noun-before-adjective, the natural French order) wasn't matched by a prefix-first-only regex. Fixed by trying both orders (mirrors the existing dual-order handling already used for the "next week" range and ordinal-of-month patterns).
• Dutch grammar: next/last only had the common-gender forms ("volgende"/"vorige"), missing the neuter forms ("volgend"/"vorig", no final "-e") needed before neuter nouns like "jaar" and the newly-added "kwartaal". Added the missing forms.

Verification

• 723/723 tests passing (139 new: per-language period-granularity tests × 12 languages, explicit Q3/2026-Q3/2026-W02 forms, parseDate() granularity-format integration, getParseCommand() week-format-vs-list-behavior, settings UI).
• Confirmed each new regression test actually catches its bug via revert-test-restore (temporarily undid each fix, confirmed the corresponding tests failed, then restored).
• npx tsc --noEmit, npx eslint, and npm run build all clean.
• CHANGELOG.md, API.md, and README.md updated.

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