Gleaner 2.2.0

• Added /gleaner:preferences for shared, versioned save destinations and formats, local-first storage, project/session overrides, and optional invocation-time Google Drive sync.
• Page and YouTube saves share first-save setup, explicit-request precedence, verified destinations, and format checks. Temporary saves never change permanent defaults.
• Added three-way sync instructions with conflict reconciliation, readback verification, pending retries, and cloud-only/session fallbacks. Project overrides and sync metadata never upload.
• Extended static validation for preferences metadata, contract references, and YAML examples; added maintainer-run acceptance scenarios. Live connector sync remains separately tested.
• Check final Markdown filenames before Drive uploads and serialize local preference writers with a shared lock to prevent overlapping invocations from discarding updates.