feat(api): add asynchronous historical import jobs

[salmonumbrella]

What changed

• Add authenticated POST /api/v1/imports and GET /api/v1/imports/{job_id} endpoints for bounded Gmail and IMAP historical imports.
• Queue imports behind the daemon's archive-operation gate, with process-local status, progress, final counts, timestamps, and sanitized failures.
• Handle SQLite timestamp precision and resumed sync runs when attributing progress and completion to a job.
• Publish schema 2.13.0 and regenerate the Go and TypeScript clients.

Why

Remote deployments can inspect and schedule accounts over HTTP, but starting a bounded initial import still requires a local msgvault sync-full bridge. This adds the missing async primitive for operator UIs without exposing arbitrary commands or provider tokens.

Usage

curl http://localhost:8080/api/v1/imports \
  -H "Authorization: Bearer $MSGVAULT_API_KEY" \
  -H "Content-Type: application/json" \
  --data '{"account":"you@example.com","after":"2024-01-01","limit":5000}'

Poll GET /api/v1/imports/{job_id} until the job reaches done or failed.

Closes #378

[roborev-ci]

roborev: Combined Review (3fb4cfc)

Verdict: No Critical, High, or Medium severity findings.

The reviewers identified no actionable issues meeting the reporting threshold.

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Reviewers: 2 done | Synthesis: codex, 5s | Total: 9m17s

[wesm]

reviewing

[wesm]

this work appears to have gotten done twice in #721 and #722, but slightly differently. the clankers appear to prefer #721, let me know what you want to do before I put work into getting one of them merged

[salmonumbrella]

#721 it is!