fix: UI layout breaks + keyboard shortcuts follow macOS HIG (#702)

[datlechin]

Summary

Two-part fix for #702: resolves UI layout breaks from menu interactions AND updates default keyboard shortcuts to follow macOS Human Interface Guidelines.

Part 1: UI Layout Fixes (12 causes addressed)

#	Fix	File
1	QuerySplitView bounds-zero crash — guard bounds.height > 0, defer collapse, clamp constraints	QuerySplitView.swift
2	Inspector HStack animation — .transaction { $0.animation = nil } blocks animation from NSSplitView	ContentView.swift
3	Filter/History panel transitions — removed .transition and .animation (instant toggle)	MainEditorContentView.swift
3b	Inspector toggle — withAnimation at call site instead of view modifier	MainContentCommandActions.swift
5	Deferred inspector update — removed 100ms Task.sleep (synchronous now)	MainContentView+Helpers.swift
6	DataGridView async writebacks — Task { @MainActor } instead of DispatchQueue.main.async	DataGridView.swift, +Editing, +Selection, DataGridCoordinator
7	Menu-bounce guard — skip lazy-load if resign+become key within 200ms	MainContentView.swift
8	Close Tab guard — only close windows with "main" identifier	TableProApp.swift
9	Find panel hack — explicit @MainActor + 50ms sleep	SQLEditorCoordinator.swift
11	Popover anchor — attachmentAnchor: .point(.bottom)	TableProToolbarView.swift

Part 2: Keyboard Shortcut Defaults

Updated 6 defaults to follow macOS HIG. Existing user customizations are preserved.

Action	Before	After	Rationale
Toggle Filters	⌘F	⌘⇧F	⌘F is "Find" (macOS HIG)
Toggle Inspector	⌘⇧B	⌘⌥I	macOS standard (Xcode, Safari)
Toggle Sidebar	⌘B	⌘0	macOS standard (Xcode, Finder)
Switch Connection	⌘⌥C	⌘⌃C	Avoids "Copy Special" conflict
Add Row	⌘I	⌘⇧N	⌘I is "Get Info" in Finder
Duplicate Row	⌘D	⌘⇧D	⌘D conflicts with "Select Word"

Test plan

• Toggle Table Browser (⌘0) — sidebar toggles without layout glitch
• Toggle Inspector (⌘⌥I) — inspector appears without NSSplitView jitter
• Toggle Filters (⌘⇧F) — filter panel appears instantly (no slide)
• Toggle Results — results collapse/restore without crash
• ⌘F in SQL editor — Find panel opens (not filter toggle)
• Click any menu while editing a cell — no column layout break
• Settings > Keyboard — new defaults shown correctly
• Customize a shortcut, restart — override preserved