Gate JSDoc completeness on every package export

New doc-sync gate verify-export-jsdoc walks every module-level exported
name under packages/*/*/src and requires description prose everywhere,
plus @param per parameter and @returns on non-void annotated returns for
function-like exports, public class methods, properties, and accessors.
The parsing + check helpers move out of gen-cordis-catalog.ts into a
shared scripts/jsdoc.ts so 'documented' means one thing on both gated
surfaces.

Deliberate exemptions (documented in the RFC): heritage-declared class
members (the seam declaration is the doc's one home — the one checker
query in an otherwise pure-AST walk), cordis plugin-protocol slots
(name/inject/reusable/Config/apply, top-level and static), constructors,
overload implementations, declare-module augmentation bodies, and
re-export statements (checked at the defining module).

The 203 under-documented exports the gate found at adoption are filled
in this change, so the gate lands green; generated catalogs/graphs are
regenerated for the shifted line pointers.

RFC: docs/rfc/implemented/process/2026-07-06-export-surface-jsdoc-gate.md

packages/subagent/subagent-fork/src/index.ts

@@ -47,6 +47,8 @@ export const Config: z<Config> = z.object({
  * empty — i.e. fresh — child). The result is contiguous from seq 0 (the live
  * log keeps `seq === index`), so it is a valid session seed; the in-flight,
  * unbalanced turn is dropped so the invariants replay accepts it.
+ * @param parent - the agent whose session log to slice.
+ * @returns the seed events, contiguous from seq 0; empty when no turn has completed.
  */
 export function completedTurnPrefix(parent: Agent): SessionEvent[] {
   const events = parent.session.events