Extension storage acceptance

This is the acceptance appendix of PRD 0009.

Completion checks

• 0.44: the new contracts pass; APIs deprecated in 0.44 still work; APIs deprecated in 0.43.1 are gone.
• The 0010 conversion gate passes before the 0.45 conversion merges.
• Local data converts without losing IDs, ordering, attachments or old URLs. Interrupted conversion resumes without duplicates. Commands during conversion get storage_converting.
• Package files are read-only. Traversal, foreign-owner access and a missing current workspace fail.
• Attachment uploads resume, verify bytes, stay out of records.list() and render in the browser.
• Artifact, ticket and report links and historical revisions open after conversion and restart.
• Affected extensions, testbench, CLI and browser consumers pass checks against the published SDK. API report, version checks, package boundaries and the packaged verifier pass. Validate affected UI with Playwright.
• 0.45: no maintained extension uses a deprecated API, every manifest accepts 0.3.0 and the old APIs are gone. The migration reader and old URL routes remain.

The isolated prototype verifies authoring examples and in-memory saves only.