Improve Sentinel event handling and observability

[HaydenTtttya]

Summary

• restrict Sentinel handling to created or renamed app bundles in the Trash
• add privacy-preserving unified logging for lifecycle, watcher, deep-link, and error events
• prevent duplicate watcher startup
• safely encode file paths in pear:// deep links

Context

Sentinel only watches ~/.Trash and contains no file-deletion code, so it cannot directly remove ~/.local/bin/claude. These changes make Sentinel activity auditable and avoid processing unrelated FSEvents while investigating reports like #581.

Logs can be inspected with:

log stream --info --predicate 'subsystem == "com.alienator88.Pearcleaner" && category == "Sentinel"'

Validation

• PearcleanerSentinel Debug target builds successfully with code signing disabled
• verified runtime unified logs for Sentinel launch and Trash watcher startup
• git diff --check passes
• full upstream app build remains blocked by pre-existing hard-coded /Users/alin/GitHub/... module-map paths; this is unrelated to the Sentinel change

Closes #581