fix(web): editing a credential's base URL or model updates the catalog rows inference uses (CL-8591)

[TheGreatAxios]

Summary

• The Credentials edit dialog wrote base URL/model into the credential's own opaque metadata, but inference resolves the base URL from the model-provider row and the model from the offering's model row — an edit changed nothing Myra actually calls.
• The dialog now finds the credential's linked model-provider (by credentialId) and patches that provider's baseURL directly. A model change mints a sibling offering and redeploys Myra onto it before retiring the old offering, since a deployed Myra run pins sourceOfferingIds in its stock launch spec and the allocation service re-resolves by those exact ids — deleting the old offering first would leave a live run pointing at a dead one.

Changes

• apps/web/src/settings/credentials-api.ts: dropped metadata from UpdateCredentialInput — name/description only.
• apps/web/src/settings/inference/api.ts: added updateModelProviderBaseURL (stock PATCH /catalog/providers/:id) and mintOfferingForModel (mints/reuses a model row for the new tag and creates a sibling offering at the same priority — it never deletes the old offering itself); added deleteOwnOffering.
• apps/web/src/settings/myra-model-redeploy.ts (new): redeployMyraForModelChange reuses the existing client deploy path (myra-deploy.ts's deployMyraSource, then the stock POST /workflows/deployments) with one offering id swapped for the new one in Myra's existing sourceOfferingIds/declaredSources; swapDeclaredOffering is the pure mapping this does. Returns false (nothing to redeploy) when Myra isn't declaring the old offering at all; throws without touching either offering if the redeploy itself fails.
• apps/web/src/settings/credentials-section.tsx: the edit dialog loads the tenant's own catalog providers/offerings/models alongside credentials, shows base URL/model fields only when the credential has a linked provider, patches the provider directly for base URL, and for a model change mints the new offering, redeploys Myra onto it, then deletes the old offering only once the redeploy succeeds. Dialog copy notes a model change restarts Myra. reload() also invalidates the Inference settings section's query key.
• apps/web/src/onboarding/provider-connect-step.tsx: resolveExistingOffering takes an optional fetchImpl so the redeploy path (and its tests) can be exercised without the global fetch.
• Unit tests: mintOfferingForModel's no-op-vs-mint branching (and that it never deletes), and swapDeclaredOffering's id/default/order-preserving swap.

Testing

• bun run check (typecheck, lint, fmt, full test suite) passes.
• Live verification against a running dev stack was not completed in this environment (no outbound network access from the sandbox); the reviewer should confirm the provider PATCH and the model-change redeploy fire correctly, and that Settings → Inference reflects the new model, before merge.

[linear-code]

CL-8591