feat(datagrid): add default row sort setting (#1284)

[datlechin]

Summary

• Adds opt-in Default row sort setting in Settings > Data Grid with three modes: No sorting (default), Primary key, First column. Closes Improve default row sorting #1284.
• New opt-in plugin protocol PluginDefaultSortProvider (no PluginKit ABI bump, uses runtime cast like PluginDiagnosticProvider). Plugins can return .suppress or .forceColumns([String]) to override the app setting.
• Sort provenance lives in SortState.source (.user vs .defaultSort). Default-applied sort does not count as "active work", so preview tabs and Cmd+Click reuse still work.

Implementation notes

• DefaultSortResolver is a pure enum with one static func, fully covered by unit tests in TableProTests/Services/DefaultSortResolverTests.swift.
• Two-pass execution: phase 1 runs without ORDER BY (schema/PK not yet known). Then applyPhase1Result resolves the default sort once PK is available and triggers a single re-run. Mirrors the existing restoreFiltersForTable pattern. Gated by TabExecutionState.didEvaluateDefaultSort so it only fires once per tab lifetime.
• User-initiated sort writes are unchanged. Any SortState constructed by user code naturally gets source: .user from the default initializer. No sprinkled flag resets at write sites.

Test plan

• Build clean in Xcode (Debug + Release).
• `swiftlint lint --strict` passes.
• Run `DefaultSortResolverTests`, all cases green.
• Open table with PK, setting = Primary key: rows sort by PK ASC, header shows indicator.
• Open table without PK, setting = Primary key: no sort, no indicator.
• Setting = First column: sorts column 0. Setting = No sorting: engine order.
• Click header to sort by another column: default sort replaced. Refresh keeps user sort.
• Triple-click header to clear sort: default does not re-apply on next refresh.
• Settings > Data Grid > Default row sort picker shows all three options with correct labels.
• Preview tab mode on: opening table B from table A (default-sort active on A) reuses the preview tab (does not open new native tab).
• Opening table B from table A after user-clicked a header on A: opens new native tab.
• Restore tabs from disk: default sort applies on first load.