cleanup(config): remove literal credential compatibility residue

Adapter schemas now carry only credential references, but the Models join, onboarding readiness, shipped overlays, SDK scaffolding, fixtures, and active decision prose still treated a redacted literal apiKey as a supported compatibility state. That residue made an unsupported field look contractual and pinned Schemastery silent-dropping as behavior.

Delete those branches and examples, and let compositions and scaffolds use adapter-owned reference and environment resolution. Do not add a tombstone validator or change generic unknown-key behavior: literal adapter credentials have no migration contract to preserve.

packages/examples/acp-demo/tests/load-path.e2e.ts

@@ -33,8 +33,6 @@ const repoTsconfig = fileURLToPath(new URL('../../../../tsconfig.json', import.m
 const CORDIS_YML = `
 - id: llm-deepseek
   name: '@deepseek-ai/dsh-llm-deepseek'
-  config:
-    apiKey: !!js process.env.DEEPSEEK_API_KEY
 - id: subprocess
   name: '@deepseek-ai/dsh-subprocess-local'
 - id: bash