fix(prime): classify compiled builds without public SDK

[rynfar]

Stock Prime Agent 0.9.5 standalone archives advertise dist/index.js but do not contain it. Pylon now identifies that exact missing public SDK entry and reports the existing ACP compatibility category, rather than a generic daemon setup failure. A missing entry in an incomplete installation is classified the same way without claiming the package is stock.

Native daemon mode still requires Pylon's frozen SDK ownership contracts and remains unavailable for stock compiled binaries. Prime text generation for titles and source-control writing still requires a compatible public SDK. The user guide states these limits. This PR does not close #728; native stock support remains unresolved.

Validation: focused Prime bridge and backend selection tests (35 passed, 2 skipped), server typecheck, changed-file lint, and diff check. Review by a separate GPT-6 Sol low agent.

Implemented with GPT-6 Sol in the Codex harness.

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1 Skipped Deployment

Project	Deployment	Actions	Updated
pylon-marketing	Ignored	Preview	Sep 24, 2026 7:25am UTC

[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	14.0 KiB	14.0 KiB	+14 B (+0.1%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.2 KiB	7.2 KiB	+6 B (+0.1%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.8 KiB	6.8 KiB	+8 B (+0.1%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	58.0 KiB	58.0 KiB	+44 B (+0.1%)	66.4 KiB	✅
Codex	Live turn messages	9	10	+1 (+11.1%)	21	✅
Claude	Total thread wire	14.0 KiB	14.0 KiB	+11 B (+0.1%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.2 KiB	7.2 KiB	−2 B (−0.0%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.7 KiB	6.8 KiB	+13 B (+0.2%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	58.9 KiB	58.9 KiB	+44 B (+0.1%)	66.4 KiB	✅
Claude	Live turn messages	9	10	+1 (+11.1%)	21	✅

Baseline: 3868597 · PR result: 5bdff3e · 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: 115.6 KiB
• Claude decoded thread snapshot: 116.3 KiB

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