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/core/agent-loop/src/agent.ts

@@ -22,6 +22,10 @@ import { isTurnOpen, lastTurnNumber, runLoop } from './loop.ts'
  * the agent/* event taxonomy — plugins never need this class.
  */
 export class ReactLoopAgent implements Agent {
+  /**
+   * The queued + steering FIFOs behind {@link send}/{@link steer}. Public so
+   * the driver loop can drain it; {@link cancel} clears it wholesale.
+   */
   readonly inbox = new Inbox()
 
   private _status: AgentStatus = 'idle'
@@ -256,6 +260,8 @@ export class ReactLoopAgent implements Agent {
    * promise (unblocking the idle wait), releases any `whenIdle` waiters, and
    * aborts the current request if any. The returned `agent.done` promise
    * resolves once the loop exits.
+   * @returns the disposer — idempotent and infallible (it runs inside the
+   *   fiber's LIFO disposal chain, where a throw would skip later disposers).
    */
   start(): () => void {
     this.done = runLoop(this.ctx, this, {