feat(datagrid): toggle filter with Cmd+F when grid is focused

[datlechin]

Summary

Cmd+F is now context-aware:

• Data grid focused (table tab): toggles the filter panel
• SQL editor focused: opens the standard Find panel
• Inspector window focused: toggles the inspector filter (existing behavior)

Cmd+Shift+F is removed as the default shortcut for "Toggle Filters". The Edit menu "Toggle Filters" item stays accessible without a default binding; users can rebind in Settings → Keyboard Shortcuts if they want their old habit back.

Why

The previous Cmd+Shift+F for filters added a modifier where most users expect a Filter shortcut to match the native Find-style Cmd+F. Inspector windows already routed Cmd+F to filter; this PR extends the same logic to the main data grid.

Changes

• TableProApp.swift "Find..." menu button: adds a branch for firstResponder is KeyHandlingTableView && actions?.isTableTab == true → toggleFilterPanel(). Editor branch unchanged.
• KeyboardShortcutModels.swift: removes the .toggleFilters default keymap entry. The action stays in the enum so users keep their saved customizations; only the factory default is gone.
• Docs updated: docs/features/filtering.mdx, docs/features/keyboard-shortcuts.mdx.
• CHANGELOG entry under Changed.

Test plan

• xcodebuild -project TablePro.xcodeproj -scheme TablePro test -skipPackagePluginValidation
• Open a table → click the data grid → press Cmd+F → filter panel toggles
• Open a query tab → click the SQL editor → press Cmd+F → editor Find panel opens
• Open the Inspector → press Cmd+F → inspector filter toggles
• On a non-table tab (welcome, ER diagram) → press Cmd+F → editor Find panel fallback (or no-op if no editor)
• Settings → Keyboard Shortcuts: .toggleFilters shows up with no default and can be assigned to any combo by the user