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/session/src/json.ts

@@ -40,6 +40,10 @@ export type JsonValue = null | boolean | number | string | JsonValue[] | { [key:
  * hiding under a symbol/non-enumerable key cannot make the round-trip lossy.
  * Getters are invoked during the check (again as `JSON.stringify` would), so the
  * contract is for plain data records, not objects with side-effecting accessors.
+ * @param value - the candidate event data to test.
+ * @param seen - objects on the current descent path, for circular-reference
+ *   detection; the recursion threads it — callers omit it.
+ * @returns true when `value` survives a JSON round-trip losslessly.
  */
 export function isJsonValue(value: unknown, seen: Set<object> = new Set()): boolean {
   if (value === null) return true