feat(gateway): add discounted Stealth Claude Opus model

[lambertjosh]

Summary

• Add Stealth: Claude Opus 4.7 (20% off) as a paid direct-provider model with a public stealth identity, third-party/training disclosure, and discounted Anthropic-style token pricing.
• Reuse the existing Stealth provider policy metadata while requiring data collection for this paid offering, so requests configured for deny/ZDR are rejected locally.
• Enable Anthropic Messages requests for the Martian gateway to support this Claude-compatible model with minimal temporary routing expansion while the existing Grok offering is retired.

Verification

• Fetched GET /api/openrouter/models from the local Cloud server and confirmed Stealth: Claude Opus 4.7 (20% off) appears in the catalog.
• Used the CLI against local Cloud with KILO_API_URL=http://localhost:3000, selected the new model, received a completion, and confirmed it reports the public model identity kilo/stealth/claude-opus-4.7.

Visual Changes

N/A

Reviewer Notes

• Current IDE/CLI clients do not render custom promotion or training badges, so (20% off) remains in the display name for this release; structured client indicators are follow-up work.
• The existing synthetic Stealth provider policy marks training and prompt retention in organization settings; the new requires-data-collection flag extends equivalent deny/ZDR enforcement to this paid training-enabled model.
• Adding /messages at the Martian provider level temporarily allows the soon-to-be-removed Grok Martian offering through that API path as an accepted simplification.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Executive Summary

The new commit (4d70dd46) makes a description-only change to claude_opus_4_7_stealth_model, rewriting the model description to lead with "Trains on your data." for clearer policy emphasis — no logic, routing, or cost changes. All previous findings remain valid and no new issues were identified.

Files Reviewed (7 files)

• apps/web/src/app/api/openrouter/[...path]/route.ts
• apps/web/src/lib/ai-gateway/models.ts
• apps/web/src/lib/ai-gateway/models.test.ts
• apps/web/src/lib/ai-gateway/providers/anthropic.constants.ts (updated in new commit — description text only)
• apps/web/src/lib/ai-gateway/providers/kilo-exclusive-model.ts
• apps/web/src/lib/ai-gateway/providers/provider-definitions.ts
• apps/web/src/lib/ai-gateway/processUsage.calculatKiloExclusiveCost.test.ts

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_{Reviewed by claude-sonnet-4.6 · 166,064 tokens}

_{Review guidance: REVIEW.md from base branch main}

[arimesser]

@lambertjosh Looks good. If a request is rejected locally (due to a ZDR policy), will the user receive a notification? Or it just won't work?

[lambertjosh]

@arimesser - it does.

I've tested:

1. A normal paid model -> Works
2. A free model that trains (nemotron) -> Blocked
3. Opus 4.7 Discounted -> Blocked