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

[DanielGGordon]

What

Claude Code 2.1.284 shipped claude-sonnet-5-5, but the Claude provider's hardcoded catalog topped out at claude-sonnet-5, so Sonnet 5.5 never appeared in the T3 model menu.

• Adds the claude-sonnet-5-5 built-in entry with the same Reasoning / Context Window options as Sonnet 5, gated on Claude Code >= 2.1.284.
• Effort defaults to Medium, matching Claude Code's baked-in catalog (default_effort: "medium" for Sonnet 5.5, vs high for Sonnet 5).
• Context Window stays 200k by default with 1M opt-in, matching Sonnet 5 (claude-sonnet-5-5[1m] is a valid id in the CLI, but 1M is not the menu default for the Sonnet family).
• No Fast Mode / Ultracode option: Sonnet 5.5's catalog entry carries neither fast_mode nor the ultracode-style capabilities, same as Sonnet 5.
• Extends the version upgrade-message chain and keeps xhigh unmapped for the new slug (it has xhigh_effort, so it must not be promoted to max).
• Points the bare sonnet alias at 5.5 (mirroring feat(claude): add Claude Fable 5.1 to the built-in model list #55/feat(claude): add Claude Opus 5.5 to the built-in model list #56 for fable/opus), adds sonnet-5.5 / claude-sonnet-5.5, and leaves sonnet-5 on claude-sonnet-5.

Why 2.1.284 for the minimum version

Confirmed empirically: claude-sonnet-5-5 is absent from the 2.1.283 binary's baked-in model catalog and present in 2.1.284 (checked by unpacking @anthropic-ai/claude-code-linux-x64 at both versions).

Verification

• vp test run apps/server/src/provider/Layers/{ProviderRegistry,ClaudeAdapter}.test.ts apps/server/src/provider/providerSnapshot.test.ts — 120 passed (includes new coverage: model shows at 2.1.284, hidden with upgrade message at 2.1.283, xhigh preserved)
• vp test run packages/shared/src/model.test.ts, apps/web/src/{modelSelection,providerInstances}.test.ts — 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.