Fix sequential PDF batch handoff

[SunChJ]

Summary

• Isolate opt-in live PDF smoke and benchmark state from the running Gloss App session.
• Wait for BabelDOC worker cleanup before handing the executor slot to the next PDF.
• Add delayed-cleanup and replay recovery coverage.
• Prepare Gloss 0.8.2 (build 10) with release notes.

Validation

• Full Swift test suite: 172 tests passed, 4 opt-in tests skipped, 0 failures
• BabelDOCExecutorClientTests: 10 passed
• Changed-Swift lint and plist validation pass
• Attention Is All You Need repeated benchmark: 15.50s with fresh layout cache, 6.61s with layout cache hit
• All 15 output pages retain selectable text; rendered pages 1, 8, and 15 were visually inspected

Compatibility

The client remains compatible with existing executor protocol runtimes and adds only a bounded post-result cleanup wait.