[iliaal]

Summary

Document the existing workbook-wide wrapper invalidation performed by ExcelSheet::removeFilter() and ExcelTable::removeFilter(). Even a no-op removal invalidates all existing autofilter/filter-column wrappers in that workbook; owners and filters in other workbooks survive. Callers must re-fetch surviving filters. No runtime behavior changes.

Add regression coverage for both sheet/table directions, no-op removals, surviving owners, re-fetched filter ranges, and workbook isolation. Test 260 runs on the supported LibXL floor; table coverage in 261 requires LibXL 5.2. Numbers avoid sibling PR #338's test 259.

Validation

• Strict native PHP 8.4.26 NTS / LibXL 5.2.0.1 build with repository developer warnings: no diagnostics.
• Final PHPT suite: 256 passed, 7 skipped, 0 failed/warned. Skips are license/platform-specific, not passes.
• Both new tests fail when both autofilter-generation bumps are omitted, and pass against unchanged runtime.
• Changed PHP documentation syntax checks and git diff --check pass; independent native/source review passed.
• Source/sibling sweep: the only autofilter-generation bump callers are these two removal APIs. Conditional-format removal uses a separate generation and is outside this focused change. No contradictory filter lifetime prose found.
• Actual merge-tree checks clean with current master and sibling PRs [Vulcan] Clarify nullable properties and indexed range warnings #337/[Vulcan] Document moveSheet wrapper invalidation #338; remote tree/modes match the locally tested tree.

Limitations: native build reused official headers/library, not a fresh phpize/configure; no local Windows/ZTS/sanitizer or performance claim. GitHub CI for exact head 89ef1c72bf19691daf16f96a3d88cd06fc0af13a completed successfully: Tests and Windows Build, 36 jobs passed, 1 release-attachment job intentionally skipped (not a pass). All 36 job logs verified against the exact-head merge commit; test summaries show zero failures/warnings. Regression 260 executes on LibXL 4.6/5.1/5.2 lanes; 261 is version-gated to 5.2; both execute in PHP 8.4 ZTS/ASAN lanes.