feat(expenses): Add create work order from expense (Story 11.6)

[daveharmswebdev]

Summary

• Add "Create Work Order" button (add_task icon) on expense rows when no work order is linked
• Dialog pre-populates description and category from the expense, creates WO via API, then auto-links the expense
• Works in both property expense workspace and all-expenses list (/expenses)
• Handles partial failure (WO created but link failed) with user-friendly messaging
• 39 new unit tests, 2,219 total passing, 0 regressions

Test plan

• Verify add_task button appears on expenses without a linked work order
• Verify button is hidden on expenses that already have a linked work order
• Click button and confirm dialog opens with pre-populated description and category
• Fill in details and click "Create & Link" - verify snackbar and row update
• Cancel dialog and verify no work order is created
• Test from all-expenses list at /expenses - same behavior
• Verify validation: empty description shows error, button disabled
• Run npm test - all 2,219 tests pass

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