fix: keyboard shortcuts

[datlechin]

Summary

Full keyboard shortcut audit against macOS Human Interface Guidelines. Fixes 3 HIG violations, 3 dead shortcuts, and 12 documentation inaccuracies.

HIG Fixes

• Remap Quick Switcher from ⌘P → ⌘⇧O (⌘P is macOS Print standard)
• Remap Format Query from ⌘⌥F → ⌘⇧L (⌘⌥F is Find & Replace in CodeEditSourceEditor)
• Add 3 missing system-reserved shortcuts to guard list (⌘⌃Q Lock Screen, ⌘⌃F Full Screen, ⌘⌥D Toggle Dock)

Wired Dead Shortcuts

• ⌘L now opens AI chat + explains current query (was defined but never wired to menu)
• ⌘⌥L now opens AI chat + optimizes current query (same)
• ⌘0 now toggles sidebar via native NSSplitViewController.toggleSidebar(_:) (same)

Documentation Fixes

• Removed 5 phantom shortcuts (F2 Edit cell, ⌘⌥Z Zoom, ⌘D Disconnect, ⌘⇧L Toggle AI Chat, ⌘? Search docs)
• Fixed 4 inaccurate descriptions (Select word→Duplicate line, Copy as CSV→Copy with Headers, etc.)
• Updated all remapped shortcut references (⌘P→⌘⇧O, ⌘⌥F→⌘⇧L)

Notes

• Existing user customizations are preserved — only default bindings change
• No migration needed — ShortcutAction enum cases unchanged

Test plan

• ⌘⇧O opens Quick Switcher
• ⌘P does nothing (no longer conflicts)
• ⌘⇧L formats query
• ⌘⌥F opens Find & Replace in editor (no longer conflicts with Format Query)
• ⌘L opens AI chat + explains current query
• ⌘⌥L opens AI chat + optimizes current query
• ⌘0 toggles sidebar
• Settings > Keyboard shows all shortcuts correctly
• "Reset to Defaults" applies new default bindings