Add managed BabelDOC runtime and PDF service dashboard

[SunChJ]

Summary

• keep an authenticated BabelDOC layout/executor service alive for the PDF workspace, with reconnect, replay-safe progress, targeted cancellation, and verified stale-process cleanup
• install and update signed BabelDOC runtimes atomically, preserve one verified rollback version, and fail closed on unsafe archives or state
• integrate the runtime lifecycle into the macOS PDF batch UI and Settings dashboard, including startup cleanup, reconnect/retry/rollback controls, multi-file drag and drop, and maintenance serialization
• bump Gloss to 0.8.0 and add dual-architecture CI and release packaging
• publish ad-hoc-signed binaries to public SunChJ/gloss-releases, then dispatch SunChJ/homebrew-tap so users can install with brew install --cask sunchj/tap/gloss
• make the custom cask re-sign nested code inside-out, preserve and compare entitlements, remove quarantine, and verify the complete installed app
• stage public assets in a draft Release and enforce immutable tags and assets after publication

Validation

• swift format lint --strict passed for every changed Swift file
• swift test --parallel passed: 171 XCTest cases plus 25 runtime-distribution tests
• swift build --configuration release passed
• release shell syntax, Actionlint, manifest/checksum generation, deterministic cask validation, Homebrew DSL loading, and Homebrew style passed
• public tap validation accepts the real generated manifest/cask contract and rejects checksum or cask-template drift
• multi-file PDF drag and drop was manually verified

Dependencies and release gates

• managed runtime publication is provided by Release signed Gloss runtime with layout reuse and telemetry SunChJ/BabelDOC#3
• public binary and tap repositories are initialized; releases are immutable, and tap main requires reviewed PRs plus the exact Cask validation status
• the tag to publish after merge is v0.8.0
• publication intentionally uses ad-hoc signing, not Developer ID or Apple notarization
• the private repository still needs GLOSS_EXTENSION_TOKEN (read-only access to SunChJ/personal-immersive-translator) and GLOSS_DISTRIBUTION_TOKEN (Contents write on gloss-releases, Actions write on homebrew-tap) before tagging