feat(admin): de-duplicate per-plugin settings out of the .env admin page

[Weegy]

What

The admin /settings page was backed by a hand-maintained catalog (settingsCatalog.ts, 31 entries) that just mirrored each plugin's own manifest.yaml → setup.fields and wrote through the exact same installedRegistry.updateConfig / vault plumbing as the per-plugin runtime editor. ~27 of 31 entries were pure duplicates of settings already editable per-plugin.

The only keys the admin page uniquely owned were 4 orchestrator model-routing knobs that were missing from the orchestrator manifest.

Changes

• Move the 4 routing knobs into the orchestrator manifest (orchestrator_model_routing + the 3 model_routing_*_model fields) in harness-orchestrator/manifest.yaml setup.fields → now editable in the per-plugin settings editor like every other orchestrator setting.
• Slim settingsCatalog.ts from 31 → 1 entry: ANTHROPIC_API_KEY, the one genuinely cross-plugin value (its secret fans out to 3 vault scopes — orchestrator, verifier, orchestrator-extras — so setting it once centrally is a real convenience the per-plugin editor can't match). Every other setting now lives with its plugin.
• Add a bilingual (next-intl, en/de) "plugin settings directory" to /admin/settings that links each plugin to its own editor at /store/<id>.
• Tests: rewrite adminSettingsRoute.test.ts for the slim catalog (Anthropic fan-out, set/unset, sk-ant- validation, unknown/not-installed paths); add orchestratorManifestRoutingFields.test.ts as a regression guard that the 4 routing fields stay in the manifest with correct types.

Why it's safe

bootstrap.ts .env→config seeding and the write plumbing are untouched. The catalog only ever drove the admin overview UI, so removing entries cannot change any runtime value — those settings remain fully editable through each plugin's own editor.

Verification

• middleware: lint clean, tsc --noEmit clean, affected tests 11/11 pass (incl. the new main buildForAgentRouting test)
• web-ui: eslint clean, tsc --noEmit clean, i18n:check OK (1096 keys, en/de parity)