feat(claude): add Claude Opus 5.5 to the built-in model list

[DanielGGordon]

What

Claude Code 2.1.280 shipped claude-opus-5-5, but the Claude provider's hardcoded catalog topped out at claude-opus-5, so Opus 5.5 never appeared in the T3 model menu.

• Adds the claude-opus-5-5 built-in entry with the same Reasoning / Fast Mode / Context Window options as Opus 5, gated on Claude Code >= 2.1.280.
• Effort defaults to Medium, matching Claude Code's baked-in catalog (default_effort: "medium" for Opus 5.5, vs high for Opus 5).
• 1M context is the default, since the CLI supports the claude-opus-5-5[1m] suffix and the model is natively 1M.
• Extends the version upgrade-message chain and keeps xhigh unmapped for the new slug (otherwise it would be silently promoted to max).
• Points the bare opus alias at 5.5 (mirroring what feat(claude): add Claude Fable 5.1 to the built-in model list #55 did for fable), adds opus-5.5 / claude-opus-5.5, and leaves opus-5 on claude-opus-5.

Why 2.1.280 for the minimum version

Confirmed empirically against installed CLI binaries: claude-opus-5-5 appears in the baked-in model catalog of 2.1.280 and is absent from 2.1.278. 2.1.279 was never published to npm, so 2.1.280 is the first release carrying the model.

Verification

• vp test run apps/server/src/provider/Layers/{ProviderRegistry,ClaudeAdapter}.test.ts — 113 passed (includes new coverage: model shows at 2.1.280, hidden with upgrade message at 2.1.279, xhigh preserved)
• vp test run packages/shared/src/model.test.ts, apps/web/src/{modelSelection,providerInstances}.test.ts, apps/server/src/provider/providerSnapshot.test.ts — all passing
• tsgo --noEmit -p apps/server/tsconfig.json — clean; vp lint / vp fmt --check on changed files — clean

🤖 Generated with Claude Code

[DanielGGordon]

Test deployment (degraded / tunnel mode)

This branch is running on a local test instance, but the external HTTPS
port is not reachable yet (Caddy not bootstrapped or OVH port closed), so
there is no public URL. Reach it over an SSH tunnel:

# Open the tunnel from your laptop (keep this session open):
ssh -L 8080:127.0.0.1:3779 dgordon@<SERVER_IP>
# THEN, inside that SSH session (i.e. on <SERVER_IP>, not your laptop),
# mint a link whose URL points at your tunnel origin:
node scripts/test-status.ts --pair 7449 --base-url http://127.0.0.1:8080
# finally open the printed http://127.0.0.1:8080/pair#token=... in your local browser

Slot: external 7449 ⇄ loopback 3779.