feat: support DSH 0.2 persistence handles

[mattheliu]

DSH 0.2.0-rc.1 removes the coordinator and ID-addressed persistence API used by the current plugin. This updates Session Teleport to the published create/open → SessionHandle contract and pins its development baseline to DSH 0.2.0-rc.1 / Cordis 4.0.4.

• Implement read/write handles, live SessionStore routing, durability barriers, teardown, local OS writer locks, typed ownership errors, and exact-batch retries after response loss. Background failures retain their batch and pause automatic retries until an explicit flush succeeds.
• Preserve fork inheritedEventCount across storage and export/import, and support empty session materialization/import/rollback. Schema 5 adds the inherited boundary without rewriting stored events. Upgrade the authority service and adapter together; a readiness check refuses older services. The adapter refuses retired session formats rather than silently relabeling them as format 4.
• Update the public dependency closure, profile lifecycle checks, migration guidance, committed build output, and CI. A new CI job boots the official DSH CLI, runs PostgreSQL 17 recovery/migration checks, and verifies profile install/cutover/uninstall.

Validation on macOS with Node 24:

• pnpm check with the official DSH CLI: 57 passed, 6 PostgreSQL-only tests skipped; includes strict type checks, build, release artifact checks, actual loader/capture probes, and a real JSONL fork export/import/restore.
• Local packaged-profile install, default/cutover composition, binary/adapter loading, and uninstall: passed.
• pnpm audit --prod: no vulnerabilities. pnpm pack:check: passed (90 files, no local npm config).
• Linux CI: both jobs passed. The integration job passed all 8 tests against the official DSH CLI and PostgreSQL 17, plus packaged-profile install/cutover/uninstall. Combined with the default suite, all 63 distinct tests have passed.

The two-commit lifecycle probe using old 0.6.0-rc.2 as the starting version stopped at the new DSH compatibility guard: DSH 0.2 correctly refuses that old plugin before installation and restores the disposable profile. No version exemption was enabled. The completed package/loader checks validate the new candidate; cross-runtime upgrades from an already installed RC.6 profile still need their own acceptance run.

Physical multi-host/WAN, database failover, and Windows operation remain outside this validation; this PR does not certify those release gates.