feat(queries): streamline table tabs and unify result footers

[Blankll]

Summary

UI polish for the Queries workspace: faster table navigation, consistent status footers, and app-wide scrollbar parity.

Table context menu

• View Data is now the first table context-menu item and behaves exactly like double-clicking the table.
• View Structure is second and opens the table tab directly on its Schema sub-page — no generated information_schema query in a separate editor.
• The selected sub-page is stored in table-view tab metadata, so reopening an existing tab switches between Data and Schema instead of creating duplicates.
• Select Top 100 remains available as the third item.

Table-view footers

• The footer now exists on every table-view sub-page, always showing the database:
  • Data — rows and execution time (unchanged)
  • Schema — column count
  • Indexes — index count
  • Foreign Keys — foreign-key count
  • Triggers — trigger count
• Metadata panels emit their count after loading, so the footer tracks tab switches and table/database changes.

Result panel footer

• Removed the duplicate 61 rows • 21ms block from the result-panel header.
• The footer is now the single source of result stats:
  • SELECT results — DataGrid footer with database, row range, and execution time.
  • Statements without a result grid (DML/DDL) — footer with database, affected rows (or “Command completed”), and execution time.
• Removed the duplicated affected-row line from the DML success body.

Editor scrollbar

• Monaco vertical/horizontal scrollbars now use the app’s 5px size instead of the 14px/12px defaults.
• Disabled Monaco scrollbar shadows.
• Matched the native scrollbar thumb: 3px radius and the same muted-foreground background (25%, 40% on hover/active).

Verification

• npm run build — passed (vue-tsc + Vite)
• npx jest --runInBand — 698 tests / 43 suites passed
• npm run lint:check — 0 errors; one pre-existing UnoCSS ordering warning in DefaultAvatar.vue
• Added tabStore coverage for opening/switching table-view tabs on a requested sub-page
• Rebuilt the Tauri app locally, ad-hoc signed it (Developer ID identity unavailable on the build machine), installed it to /Applications/SQLKit.app, and verified the running build embeds the updated frontend asset.

Notes

• The whole application status bar was removed rather than only its Database item, since its rows/time values are now duplicated in the table/result footers.
• This PR does not include a release/version bump.