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.

packages/util/retention/src/index.ts

@@ -211,8 +211,7 @@ const decoder = new TextDecoder() // utf-8, non-fatal: internal malformed bytes
 function trimTrailingPartialUtf8(bytes: Uint8Array): Uint8Array {
   let i = bytes.length - 1
   // Continuation bytes are 0b10xxxxxx; scan back at most 3 (max sequence is 4).
-  // Indices are bounds-checked by the loop guard, so the reads are in range (a
-  // cast, not `!`, per the repo's no-non-null-assertion rule).
+  // Indices are bounds-checked by the loop guard, so the reads are in range.
   while (i >= 0 && ((bytes[i] as number) & 0xc0) === 0x80 && bytes.length - i <= 3) i--
   if (i < 0) return bytes
   const lead = bytes[i] as number
@@ -228,7 +227,7 @@ function trimTrailingPartialUtf8(bytes: Uint8Array): Uint8Array {
  */
 function trimLeadingContinuationUtf8(bytes: Uint8Array): Uint8Array {
   let i = 0
-  // i < length guards the read; cast rather than `!` (no-non-null-assertion).
+  // i < length guards the read.
   while (i < bytes.length && ((bytes[i] as number) & 0xc0) === 0x80) i++
   return bytes.subarray(i)
 }