Add JSDoc completeness gate for the cordis surface

gen-cordis-catalog now hard-errors (aggregated, not fail-fast) when an
event lacks description prose or a payload @param, or a public service
method lacks JSDoc, a @param per parameter, a @returns on a non-void
result, or an explicit return type annotation. The this receiver and the
trailing waterfall next are exempt on events (mode machinery owned by
@mode); a stale @param naming no real parameter errors, mirroring the
@mode contradiction check. parseJsDoc now ends prose at the first block
tag (standard JSDoc semantics), so the tags never change the rendered
catalog — only Source: line pointers moved.

Fills the ~139 gaps found across the 15 surface files, extends the spec
with negative-path fixtures for every new guard plus the exemptions,
records the decision as an implemented process RFC, and extends the
AGENTS.md typed-events bullet with the authoring rule. Runs inside
verify-cordis-catalog -> doc-sync, so CI and pre-push enforce it with
zero new wiring.

packages/compact/compact/src/index.ts

@@ -141,6 +141,7 @@ export abstract class CompactService extends Service {
    *   prior replace can leave the surface non-monotonic in seq order), or if
    *   either boundary is not a balanced tool-pairing cut (would split a step's
    *   tool-call/result pair).
+   * @returns what the compaction did (the replaced range and its summary node).
    */
   abstract compactRegion(
     session: Session,