refactor: preamble, co-author trailer, and resolver suppression use host configs

- preamble.ts: hostConfigDir derived from config.globalRoot instead of
  hardcoded Record
- utility.ts: generateCoAuthorTrailer reads from config.coAuthorTrailer
  instead of host switch statement
- gen-skill-docs.ts: suppressedResolvers from config skip resolver
  execution at placeholder replacement time (belt+suspenders with
  existing ctx.host checks in individual resolvers)

Golden-file comparison: all 3 hosts produce IDENTICAL output to baselines.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

hosts/claude.ts

@@ -38,7 +38,7 @@ const claude: HostConfig = {
     linkingStrategy: 'real-dir-symlink',
   },
 
-  coAuthorTrailer: 'Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>',
+  coAuthorTrailer: 'Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>',
   learningsMode: 'full',
 };
 

hosts/codex.ts

@@ -32,12 +32,11 @@ const codex: HostConfig = {
   ],
 
   suppressedResolvers: [
-    'DESIGN_OUTSIDE_VOICES',
-    'ADVERSARIAL_STEP',
-    'SPEC_REVIEW_LOOP',
-    'PLAN_VERIFICATION_EXEC',
-    'CODEX_SECOND_OPINION',
-    'REVIEW_ARMY',
+    'DESIGN_OUTSIDE_VOICES',  // design.ts:485 — Codex can't invoke itself
+    'ADVERSARIAL_STEP',       // review.ts:408 — Codex can't invoke itself
+    'CODEX_SECOND_OPINION',   // review.ts:257 — Codex can't invoke itself
+    'CODEX_PLAN_REVIEW',      // review.ts:541 — Codex can't invoke itself
+    'REVIEW_ARMY',            // review-army.ts:180 — Codex shouldn't orchestrate
   ],
 
   runtimeRoot: {