Adds a "Validate" button that calls the existing `validateImportBatch`
tRPC query before staging. Shows a readiness report inline:
- Green/amber/red status line based on canCommitWithStrictSourceData
- Record counts (resources, projects, assignments, vacations)
- Blocker issues in red with resolution hints
- Warnings in amber with resolution hints
- Fallback assumptions listed in gray
Also fixes a pre-existing bug where handleSubmit mapped wrong filePaths
keys to API fields (keys are resources/projects/assignments, not the
API field names).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>