## Why
Configured filesystem paths can be slow or inaccessible. Doctor needs to identify those paths and their configuration sources without letting a blocked filesystem call delay runtime shutdown.
## What changed
- Add `sandbox.filesystem_paths` to report literal filesystem grants, access modes, resolution outcomes, and configuration sources when available. Exclude deny rules and denied paths without expanding globs or special paths.
- Resolve paths in disposable helper processes, with wait budgets of two seconds per path and eight seconds total, checking at most 32 paths. Warn on slow or unsuccessful probes and incomplete checks; missing paths alone do not trigger warnings. Probes do not test read/write access.
- List paths without probing on Windows or when filesystem read restrictions apply.
- Increase the app-server doctor report timeout from 25 to 35 seconds to accommodate the probes.
## Testing
Add unit and integration coverage for path deduplication and deny filtering, configuration provenance, blocked-helper timeouts, helper execution without loading configuration, and report snapshots for resolved, missing, Windows, and read-restricted paths.
GitOrigin-RevId: b0732265fc2c83ea67acc24b442e39139d705f1b
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