fix(hooks): address Codex review — tighten codec to the reference schemas, preserve stdout

Codex's PR-E review found three protocol-fidelity blockers + two doc gaps, all
verified against ~/repos/refs:

- (A) Top-level `decision` accepted allow/deny/ask, but both reference schemas
  reserve those for hookSpecificOutput.permissionDecision — the legacy top-level
  decision is approve/block ONLY. Split topLevelDecisionOf (approve/block) from
  permissionDecisionOf (allow/deny/ask), so an out-of-band {"decision":"deny"} is
  now invalid and ignored instead of becoming a real blocking decision.
- (A) hookSpecificOutput was parsed without its hookEventName discriminator.
  HookOutput now surfaces hookEventName so a bridge can discard a block whose
  claimed event doesn't match the firing one (the schemas key the block by event).
- (A) runHook discarded raw stdout. HookOutput now carries `stdout` (trimmed,
  verbatim) so a bridge can reproduce CC's plain-stdout rendering / Codex's
  plain-stdout-as-additionalContext behavior.
- (B) hook/* SessionEventMap variants were only named in prose; added a payload/role
  table to core-data-structures/session.md (a maintained catalog surface).
- (B) Removed PR-stack-position references (PR-F / "future bridge packages") from a
  test comment and the RFC, per the current-state-wording rule.

New codec tests: top-level allow/deny/ask invalid+ignored, hookEventName capture,
raw stdout preserved on plain + JSON + empty stdout. 51 tests, per-file 100%.

packages/hooks/hook-protocol/tests/runner.spec.ts

@@ -6,8 +6,8 @@ import { runHook } from '@deepseek-ai/dsh-hook-protocol'
  * A minimal stand-in for the bits of {@link BashExecutor} that {@link runHook}
  * actually calls (`resolve` then `run`). `runHook` is pure plumbing over those
  * two methods, so a duck-typed recorder is the right test seam — the REAL
- * executor (dsh-bash-local) is exercised end-to-end by the bridge e2e tests in
- * PR-F, not here.
+ * executor (dsh-bash-local) is exercised end-to-end by the hook-bridge plugins
+ * that consume this library, not here.
  */
 function recordingBash(run: (spec: BashExecSpec) => Promise<BashRunResult>): {
   bash: BashExecutor