[HugoXK]

Written-by: HugoXK

Replaces the flat model catalog with provider to models.

• Settings now manages providers (base URL, encrypted key, private/HTTP) and multiple models per provider.
• Adding a model runs a 1-token test from Fledge; failure is an error and nothing is saved.
• Repository settings select provider models and a default; the instance patch groups them under DSH providers.
• Gateway routes an alias to its provider/key/model; legacy user models and own_llm migrate at startup.
• Add provider/model, migration, mandatory-test and instance-patch tests.

Ran:

• npm run check — pass (134 tests, build)
• node scripts/version.mjs check — pass
• node scripts/changelog.mjs check — pass
  Not run: production deploy.

No-issue: model configuration redesign from the production review.

[HugoXK]

Verdict: PASS at 9e296fc
Written-by: Reviewer
Posted-by: HugoXK

Ran:

• npm run check — pass (134 tests, build)
• node scripts/version.mjs check — pass
• node scripts/changelog.mjs check — pass
  Not run: production deploy.

Adding a model is fail-closed on the platform test; legacy rows migrate at startup.