chore: Verify DH-21375 implementation matches plan document

[Copilot]

Analyzed implementation against the plan document from PR #1282 to identify discrepancies.

Findings

Implementation is highly aligned with plan:

• ✅ API design (TableFormat.mode, TableDatabar dataclass, validation rules)
• ✅ JavaScript integration (extractDatabarsFromFormatRules, type checking)
• ✅ Comprehensive E2E tests (basic, conditional, priority, mixed formatting, legacy API)
• ✅ Documentation under "Formatting" section with new API examples

One minor gap:

• ⚠️ Missing dedicated migration guide section in docs showing before/after examples side-by-side

The plan specified a migration section like:

## Old (deprecated)
ui.table(t, databars=[{"column": "Price", "color": "positive"}])

## New  
ui.table(t, format_=[ui.TableFormat(cols="Price", mode=ui.TableDatabar(color="positive"))])

Deprecation is documented in docstrings and console warnings but not as a standalone user-facing migration guide in table.md.

Summary

95%+ plan compliance. Core functionality, validation, testing, and API design match specifications. Only missing element is explicit migration documentation for users upgrading from deprecated API.

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