feat: add agent sesison migrate endpoint

[thesujai]

Summary

add agent sesison migrate

Closes #NA

Changes

add agent sesison migrate

How was this tested?

Checklist

• I have read the contributing guidelines
• pnpm build, pnpm test, pnpm typecheck, pnpm lint:ci, and pnpm format:check pass locally
• Tests added/updated where it makes sense
• No hand-edits to generated code (packages/trueforge-sdk, .github/fern/openapi/openapi.json, docs/openapi.json) — fork PRs omit SDK regen; maintainers regenerate after merge
• Docs / .env.example updated if configuration or behavior changed

---

Note

Medium Risk
Admin-gated but can bulk-write production session data; incorrect snapshots could corrupt history, though normal session runtime paths are unchanged.

Overview
Adds an ops/backfill admin API to import a single historical agent session (session row, turns, threads, context logs, capability state, and events) into Postgres in one transaction.

POST/api/v1/settings/sessions/import is mounted under the existing settings admin surface (withAdminAuth). The body is a loose Zod-validated snapshot (session + at least one turn). If session_id already exists, the handler returns 200 with imported: false; on a successful insert it returns 201 with imported: true. Standalone/SQLite deployments wire sessionSnapshotImporter as undefined and respond with 501.

Implementation is PostgresSessionSnapshotImporter, which uses ON CONFLICT DO NOTHING on the session row and rebuilds per-thread context_ids with append-only deduplication via isContextPrefix. OpenAPI docs and a changeset are included; the route is marked x-fern-ignore (not SDK-published).

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[changeset-bot]

🦋 Changeset detected

Latest commit: 11510b8

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@truefoundry/trueforge	Patch

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[cursor]

Per-row queries inside import loops

Low Severity

The import issues a separate insert for every turn, thread, context batch, capability map, and event list. That is an N+1 write pattern inside one transaction instead of batched inserts.

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[cursor]

Cursor Bugbot has reviewed your changes using default effort and found 2 potential issues.

There are 3 total unresolved issues (including 1 from previous review).

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