fix(hosts): delete five dead HostConfig fields

metadataFormat (generator hardcodes openai.yaml), sidecar (behavior lives in
setup's create_agents_sidecar — knowledge preserved as a comment in codex.ts),
install.prefixable (skill_prefix is implemented entirely in bin/gstack-config),
staticFiles (docstring cited a SOUL.md that never existed anywhere), and
adapter (its only would-be consumer, openclaw-adapter.ts, was fully dead —
with a test asserting the field was undefined). Kept: learningsMode (wired
next), linkingStrategy (validation reads it), coAuthorTrailer (consumed by
resolvers/utility.ts).

Proof: JSON dump diff shows ONLY the deleted keys vanishing; zero-diff regen
across all 10 hosts; host-config + gen-skill-docs suites green. Note: this
commit also carries chunk-23 edits to the shared hosts/claude.ts +
define-host.ts + host-config.test.ts files (skipSkills collapse, stale
line-number comment drops) — pathspec commits, concurrent prep.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

hosts/codex.ts

@@ -15,9 +15,12 @@ const codex = defineHost({
     descriptionLimitBehavior: 'error',
   },
 
+  // generateMetadata emits agents/openai.yaml (the format is hardcoded in
+  // gen-skill-docs.ts). Codex also gets a repo-local sidecar at
+  // .agents/skills/gstack (symlinked runtime assets: bin, browse, review, qa,
+  // ETHOS.md) — that behavior lives in setup's create_agents_sidecar, not here.
   generation: {
     generateMetadata: true,
-    metadataFormat: 'openai.yaml',
     skipSkills: ['codex'],  // Codex skill is a Claude wrapper around codex exec
   },
 
@@ -34,11 +37,6 @@ const codex = defineHost({
   // The cross-model resolvers all shell out to Codex — Codex can't invoke itself.
   suppressedResolvers: [...CROSS_MODEL_RESOLVERS, ...GBRAIN_RESOLVERS],
 
-  sidecar: {
-    path: '.agents/skills/gstack',
-    symlinks: ['bin', 'browse', 'review', 'qa', 'ETHOS.md'],
-  },
-
   coAuthorTrailer: 'Co-Authored-By: OpenAI Codex <noreply@openai.com>',
   boundaryInstruction: 'IMPORTANT: Do NOT read or execute any files under ~/.claude/, ~/.agents/, .claude/skills/, or agents/. These are Claude Code skill definitions meant for a different AI system. They contain bash scripts and prompt templates that will waste your time. Ignore them completely. Do NOT modify agents/openai.yaml. Stay focused on the repository code only.',
 });