docs: purge chain-of-thought leakage from prose

Delete design-session citations (decision/audit/plan ordinals, stack
positions), change narration, review choreography, and reviewer-addressed
justification from comments, JSDoc, docs, READMEs, Agent Notes, tests, and
generator templates; restate every affected fact as current-state contract
prose. Fix generated docs at their sources and regenerate the catalogs and
cordis-surface regions; re-paste type-equiv blocks; update every bilingual
counterpart and re-record the pairs. Record the citation rule in the
committed-artifact-citations Agent Note.

docs/subsystems/session.md

@@ -171,7 +171,7 @@ interface EpochHeader {
 }
 ```
 
-Canonical form represents an empty system prompt or tool list as an absent field, matching how requests are built. Legacy v0 logs containing the removed `request/header-delta` event or its full-snapshot `fallback` reason are rejected at seed, append, and persistence-load boundaries rather than replayed incompletely.
+Canonical form represents an empty system prompt or tool list as an absent field, matching how requests are built. Legacy v0 logs containing the legacy `request/header-delta` event or its full-snapshot `fallback` reason are rejected at seed, append, and persistence-load boundaries rather than replayed incompletely.
 
 ### The route capacity event: `request/context`
 
@@ -266,7 +266,8 @@ type SurfaceEventType =
  *   (inclusive) through `end` (inclusive) with this node. Both must exist as
  *   surface nodes in the current surface. `start === end` replaces a single
  *   node. The node's {@link SessionEvent.sourceEventSeqs} must include every
- *   shadowed surface node. Used by compaction and possible other manipulations.
+ *   shadowed surface node. Used by compaction; any surface-replacing producer
+ *   may use it.
  */
 type SurfaceOp =
   | 'append'