fix(desktop): replace stale local client sessions on restart

[rynfar]

Restarting the desktop server could leave another stale local desktop client in Connections. A new local desktop bootstrap now replaces previous bearer sessions for the same subject and method in one transaction, while paired clients and browser sessions remain authorized.

Ports upstream eb77683e5544e071db74831bae052bbd8a7d5f88. If insertion fails, rollback keeps the previous credential valid. Session change events are emitted after persistence succeeds.

Validation: 182 focused EnvironmentAuth, SessionStore, and server router tests; server typecheck; changed-file lint. Includes simultaneous bootstrap, preservation of paired clients, and a forced insert failure.

Model: GPT-6 Astra. Harness: Codex.

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[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	13.7 KiB	13.7 KiB	−81 B (−0.6%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.1 KiB	7.1 KiB	+4 B (+0.1%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.6 KiB	6.6 KiB	−85 B (−1.2%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	57.3 KiB	56.5 KiB	−822 B (−1.4%)	66.4 KiB	✅
Codex	Live turn messages	8	8	0 (0.0%)	21	✅
Claude	Total thread wire	13.6 KiB	13.8 KiB	+171 B (+1.2%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.1 KiB	7.1 KiB	−8 B (−0.1%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.5 KiB	6.7 KiB	+179 B (+2.7%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	57.3 KiB	58.2 KiB	+928 B (+1.6%)	66.4 KiB	✅
Claude	Live turn messages	8	10	+2 (+25.0%)	21	✅

Baseline: 44b632a · PR result: cc81eca · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 111.2 KiB
• Claude decoded thread snapshot: 111.9 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.