feat: chunk annotations system + fix audit highlight (#23, #262 partial)

[nikazzio]

Summary

• Introduces a typed, per-chunk annotation system for the review phase
• Users can add multiple annotations per chunk (comment, doubt, problem, approved), each with optional markdown content and an anchor phrase
• Anchor phrases are highlighted in the translation editor with type-specific colors
• Chunk grid dots and index list show colored visual indicators when annotations are present
• Annotations persist in a new annotations SQLite table and survive pipeline re-runs

Also fixes (#262 partial):

• Audit phrase highlight clears when issue is marked resolved/rejected
• Locate-in-text button is now a toggle (click again to deactivate)
• Navigating to a different chunk clears the active audit highlight
• Chunk summary panel shows aggregated translation/audit stats (all stages combined) instead of only the last single stage

Closes

Closes #23 — partial fix for #262

Changes

Area	What changed
DB	New annotations table (idempotent CREATE IF NOT EXISTS)
Types	AnnotationType, Annotation in types.ts
Store	New annotationsStore.ts — CRUD + load/clear lifecycle
Project lifecycle	openProject, switchPipeline, closeProject load/clear annotations
Highlight	useGlossaryHighlight extended with annotationAnchors param
CSS	4 new hl-annot-* CSS vars + mark classes
UI	NotesTab rewritten — inline add/edit form, typed cards
UI	Chunk grid dots get colored badge when chunk has annotations
UI	IndexTab shows note count badge with priority color
UI	Audit highlight clears on resolve/reject and chunk navigation
Stats	ChunkSummaryTab shows aggregated per-category stats
i18n	annotations.* keys + updated chunk summary labels

Test plan

• App starts without errors — annotations table created
• Add annotation of type Problem → red card, chunk dot red badge
• Add annotation with anchor → phrase highlighted in translation editor
• Edit and delete annotation → updates reflected immediately
• Close and reopen project → annotations persisted
• Locate-in-text on audit issue → click again → clears highlight
• Mark audit issue as resolved → highlight disappears
• Navigate to different chunk → audit highlight clears
• Chunk summary panel → "Traduzione" card shows totals across all stages

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