fix(claude): enable subscription login by default

[yaacovcorcos]

Problem

Scient already implements Claude Code's official Claude.ai subscription flow, but a deployment environment gate hid it from normal users and made Anthropic Console the only assisted option.

Fix

• advertise Claude subscription login by default for ordinary Claude Code configurations
• keep Anthropic Console as the alternative and preserve external API/backend behavior
• update focused backend and frontend tests around the existing flow
• remove the obsolete restriction and approval language from user and internal documentation

Validation

• 32 focused Claude provider and setup tests passed
• vp run --filter t3 typecheck
• vp run --filter @t3tools/web typecheck
• changed-file lint and formatting checks
• git diff --check
• repository audit found no remaining restriction, approval-gate, or removed environment-variable references

Implemented with Factory Droid.

[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	11.3 KiB	11.4 KiB	+7 B (+0.1%)	15.1 KiB	✅
Codex	Thread snapshot wire	5.5 KiB	5.5 KiB	0 B (0.0%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	5.9 KiB	5.9 KiB	+7 B (+0.1%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	49.7 KiB	49.7 KiB	0 B (0.0%)	66.4 KiB	✅
Codex	Live turn messages	16	16	0 (0.0%)	21	✅
Claude	Total thread wire	11.3 KiB	11.4 KiB	+18 B (+0.2%)	15.1 KiB	✅
Claude	Thread snapshot wire	5.5 KiB	5.5 KiB	+5 B (+0.1%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	5.8 KiB	5.9 KiB	+13 B (+0.2%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	50.6 KiB	50.6 KiB	0 B (0.0%)	66.4 KiB	✅
Claude	Live turn messages	16	16	0 (0.0%)	21	✅

Baseline: 245e357 · PR result: 0e1bbca · 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: 94.7 KiB
• Claude decoded thread snapshot: 95.4 KiB

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