feat: highlight + comment annotations with right-click context menu

[abdullah4tech]

Summary

• Right-click context menu on selected text now includes a Highlight… option alongside Copy / Cut / Paste
• Selected text gets a coloured background overlay rendered directly in the editor (yellow, green, blue, pink, or orange)
• Each highlight can carry an optional comment/annotation — shown as a tooltip on hover and in the highlights panel
• All highlights are persisted per note in a new SQLite highlights table and survive app restarts

What changed

db.go

• New Highlight struct
• New highlights table in initDB
• dbGetHighlights, dbAddHighlight, dbDeleteHighlight query helpers

app.go

• GetHighlights, AddHighlight, DeleteHighlight Wails-bound methods

frontend/dist/index.html

• Transparent-background textarea + #hl-overlay mirror div renders <mark> spans with coloured backgrounds; scroll-synced and word-wrap-aware
• Right-click context menu (Copy / Cut / Paste / Highlight…) — "Highlight…" and its divider only appear when text is selected
• Floating colour-picker dialog with 5 swatches + comment textarea; Save on Enter, dismiss on Esc or outside click
• Highlights panel — right-side drawer toggled from the toolbar; lists all highlights for the open note with jump-to and delete per entry
• Ctrl+H keyboard shortcut retained for power users
• Highlights reload when switching notes and clear when a note is deleted

Test plan

• Open a note, select some text, right-click → Highlight… appears in the context menu
• Pick a colour, type a comment, hit Save — text shows a coloured background in the editor
• Close and reopen the app — highlights persist
• Click the Highlights toolbar button — panel opens listing the highlight; click it to jump to the text
• Delete a highlight from the panel — overlay clears
• Edit text before/after a highlight — background follows the text correctly
• Ctrl+H with selected text opens the same picker
• Right-click with no selection — Highlight… option is hidden, Copy/Cut are disabled

🤖 Generated with Claude Code

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✨ Finishing Touches

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