fix(server): explain Claude pauses and terminal failures

[rynfar]

Claude can pause at a subscription limit or abandon a request without explaining the outcome. This updates the Claude Agent SDK to 0.3.260, marks terminal failures with a readable reason, and shows quota pauses and model-fallback notices in the thread.

Adopts upstream #9135, #8853, and #7165. The quota port preserves Pylon's raw telemetry, exact turn admission, session incarnation guards, and Prime recovery. Pause notices are deduplicated per turn and quota window; overage and idle sessions stay quiet. All clients use the existing warning event.

Validation: 96 Claude adapter tests and 81 runtime-ingestion tests pass; server typecheck, targeted formatting and lint pass. The four mobile diff-highlighter tests that included the previous CI failure pass locally; current CI still needs to finish. No live provider session or UI was launched.

The upstream ledger records this partial adoption without advancing the review cursor. OpenCode approval and server-restart recovery work remain separate.

Original SDK work: Claude Fable 5.1 through Pylon (Claude Code). Follow-up integration and verification: GPT-6 Astra through Codex.

The durable implementation and review record is consolidated in companion #279.

[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	13.6 KiB	13.6 KiB	+5 B (+0.0%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.1 KiB	7.1 KiB	−3 B (−0.0%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.5 KiB	6.5 KiB	+8 B (+0.1%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	56.5 KiB	56.5 KiB	0 B (0.0%)	66.4 KiB	✅
Codex	Live turn messages	8	8	0 (0.0%)	21	✅
Claude	Total thread wire	13.6 KiB	13.7 KiB	+4 B (+0.0%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.1 KiB	7.1 KiB	+5 B (+0.1%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.6 KiB	6.6 KiB	−1 B (−0.0%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	57.3 KiB	57.3 KiB	0 B (0.0%)	66.4 KiB	✅
Claude	Live turn messages	8	8	0 (0.0%)	21	✅

Baseline: de8d090 · PR result: d5b9c15 · 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.