In-place provider editor + in-UI copy dialogs

[e3ndr]

In-place provider editor + in-UI copy dialogs (work order: ash/provider-editor-ui)

What

• Backend (RouteProviders): PATCH /api/providers/:id = remove the existing reference + re-insert the updated provider (no provider code touched for edits; Providers.create re-sanitizes the config via serializeConfig). 404 on unknown id, 400 on invalid JSON/type. The list API (GET /api/providers) now also returns url + apiKey (only when present) so the editor can prefill.
• UI (Svelte 5):
  • New minimal modal system: Modal.svelte (backdrop click + Escape close, a11y roles) and CopyModal.svelte (read-only field + Copy via navigator.clipboard with a legacy fallback for non-secure http contexts).
  • InferenceProviderEditor.svelte: prefilled in-place editor (type / pool / url / api key). The id field is read-only — model aliases and in-flight state reference it.
  • InferenceProviderCard gains an Edit button; the page holds editingProvider state and re-renders the provider list after save.
  • Both window.prompt() copy dialogs (API key create, model alias copy) are now in-UI CopyModals.

Verification

• mvn package green (Svelte build included); svelte-check 0 errors / 0 warnings.
• Dev loop: jar (fresh build) + dummy OLLAMA provider pointed at a mock backend + vite dev + chromium — full flows exercised: editor prefill, edit + save round-trip (card re-render), both copy modals incl. the clipboard "Copied" toggle. Screenshot composite DM'd.

Branch base: main @ bb2bf8a. (Concurrency fields are on ash/pool-concurrency / PR #1 — not on this branch by design.)

~Ash