Config Settings Window

read_when: changing config UI, config save behavior, or config docs

Intent

Add a dedicated Electron settings window for editing canonical config values without exposing the historical layout mistakes in config.jsonc.

The UI groups options by workflow:

Each field maps back to its current raw config path. The presentation layer must stay separate from generated config-template sections.

Settings writes use jsonc-parser.modify, not JSON.stringify.

Required behavior:

Preserve comments, trailing commas, unrelated keys, and hidden legacy keys.
Reset removes the explicit path so defaults resolve normally.
Validate the candidate config before writing.
Reject warnings caused by modified fields.
Preserve unrelated existing warnings and return them in the snapshot.
Write atomically, reload ConfigService, classify with existing hot-reload logic, and apply live changes where supported.
Never return secret values to the renderer; snapshots only expose configured/not-configured state.

Do not expose these as first-class controls:

ankiConnect.deck
Legacy top-level Anki migration fields such as wordField, audioField, media-generation aliases, and behavior aliases
Legacy ankiConnect.nPlusOne.* aliases except canonical nPlusOne.nPlusOne and nPlusOne.minSentenceWords
Deprecated Lapis sentence-card fields
youtubeSubgen.primarySubLanguages
anilist.characterDictionary.refreshTtlHours
anilist.characterDictionary.evictionPolicy
jellyfin.accessToken
jellyfin.userId
controller.buttonIndices as a normal editable field

Minimum targeted checks:

bun test src/config/settings/registry.test.ts src/config/settings/jsonc-edit.test.ts src/settings/settings-model.test.ts src/main/runtime/config-settings-window.test.ts
bun run test:config
bun run typecheck
bun run build

If docs changed: