Seed catalog offerings so Anthropic defaults to claude-sonnet-5 (CL-7294)

[TheGreatAxios]

Fixes CL-7294

Catalog seeding used one priority per provider, so every Anthropic model tied at 0 and runtime localeCompare picked claude-fable-5 over the declared default. Offerings now get distinct priorities from the flattened CATALOG_SEEDS order (claude-sonnet-5 is index 0), and a 409 reconciles via GET then PATCH instead of skipping forever.

Supersedes #546 (stale hub-client branch; that package is gone on main).

[TheGreatAxios]

Self-review

Verdict: the fix correctly flattens offering priorities across providers so Anthropic's declared default gets the lowest distinct priority, and the 409-path GET+PATCH reconciliation matches the actual hub route (cursor-paginated GET, PATCH accepting priority). No defects found; nothing changed.

• CONFIRMED-FIXED: none needed — reviewed the diff against vendor/intx/hub-api/src/routes/model-offerings.ts and found the new pagination/PATCH usage matches the real route contract exactly.
• DISMISSED: Ollama's dynamically-probed model count could in theory exceed the static CATALOG_SEEDS.ollama.models.length used to compute the priority offset for providers declared after it, reintroducing a priority collision. Not a live bug: ollama is the last key in CATALOG_SEEDS, so no provider's offset depends on its static count today.
• DISMISSED: as casts on body in the new/updated test fixtures are test-only fake-handler code, not production trust-boundary parsing.

Targeted tests run:

• bun test packages/seeding/test/seed.test.ts — 45 pass, 0 fail
• bun test packages/onboarding/test/complete-credential.test.ts packages/onboarding/test/huggingface-connect-routes.test.ts packages/onboarding/test/openrouter-connect-routes.test.ts — 53 pass, 0 fail
• bun run typecheck — clean

[linear-code]

CL-7294