chore: remove the Messages Glass Lab experiment

[rynfar]

Problem

experiments/messages-glass-lab/ was an unused iOS glass-effect scratch project inherited from upstream. Nothing in the repository references it.

Fix

Adopts upstream #8599 (ac3a33191) from the f94a0d646..1f8ed54ad T3 review: deletes the three Swift/Xcode files. Upstream's commit also carried peer-resolution hash churn in pnpm-lock.yaml; that resolved to Pylon's existing lockfile, so this commit is deletions only (3 files, 681 lines).

Verification

• git show --stat HEAD shows only the three experiment files.
• git diff origin/pylon -- pnpm-lock.yaml is empty.
• grep -rn messages-glass-lab across the tree finds nothing.
• Independent review pass: no findings.

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Claude Fable 5 in Pylon.

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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	13.3 KiB	13.3 KiB	+32 B (+0.2%)	15.1 KiB	✅
Codex	Thread snapshot wire	6.9 KiB	6.9 KiB	+1 B (+0.0%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.4 KiB	6.4 KiB	+31 B (+0.5%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	55.5 KiB	55.6 KiB	+44 B (+0.1%)	66.4 KiB	✅
Codex	Live turn messages	9	10	+1 (+11.1%)	21	✅
Claude	Total thread wire	13.3 KiB	13.3 KiB	−7 B (−0.1%)	15.1 KiB	✅
Claude	Thread snapshot wire	6.9 KiB	6.9 KiB	+1 B (+0.0%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.4 KiB	6.4 KiB	−8 B (−0.1%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	56.4 KiB	56.4 KiB	0 B (0.0%)	66.4 KiB	✅
Claude	Live turn messages	10	10	0 (0.0%)	21	✅

Baseline: abe70a7 · PR result: 75a53a9 · 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: 109.4 KiB
• Claude decoded thread snapshot: 110.1 KiB

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