test: add E2E tests for database table column resize (#1100)

[sw-factory-automations]

Closes #1100

What

Adds E2E test coverage for the database table column resize feature (drag column border to change width). This was an untested interactive feature that could only be properly verified in a real browser.

How

• Added data-testid="db-table-resize-handle-{colIndex}" to the resize handle in table-column-header.tsx for reliable test targeting
• Created e2e/database-column-resize.spec.ts with 4 tests:
  1. Drag to increase width — drags resize handle right, verifies column widens
  2. Drag to decrease width — drags resize handle left, verifies column shrinks
  3. Minimum width constraint — drags far left, verifies width stays ≥ 80px
  4. Other columns unaffected — resizes one column, verifies adjacent column width unchanged
• Follows the setup/teardown pattern from database-column-reorder.spec.ts
• Uses Playwright page.mouse.move()/down()/up() for drag simulation with stepped moves

Testing

• pnpm lint — 0 errors
• pnpm typecheck — passes
• pnpm test — 142 files, 1909 tests passed
• pnpm test:e2e --grep "column resize" — 4/4 passed
• Updated .agents/quality.md with new test counts (81 E2E specs, 397 tests)

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Project	Deployment	Actions	Updated (UTC)
memo	Ready	Preview, Comment	May 14, 2026 10:48pm

[sw-factory-automations]

[shepherd:conflict] Merge conflicts resolved and rebased on main. Conflicts were in .agents/quality.md (additive — both sides updated test counts). All checks pass (lint, typecheck, 1909 tests).

[sw-factory-automations]

✅ Post-merge verification skipped — test: PR does not affect the live app.

[sw-factory-automations]

✅ UI verification passed — no visual changes detected.

This PR adds E2E tests and a data-testid attribute to table-column-header.tsx. The only component change (data-testid) has no visual impact. Design spec compliance check not required.