fix(docs): address Codex review on the architecture rewrite

- session.md § TurnEndReasonMap now carries the full precedence rule
  the old architecture.md stated and the loop implements (loop.ts's
  stepFinishReason carry-forward): max-tokens wins over completed only;
  disposed/aborted/error take precedence. The architecture.md pointer
  was otherwise citing an incomplete home.
- The cookbook feature-map compaction row no longer reads as if a
  model-facing /compact tool ships: a manual trigger invokes the same
  ctx.compact routine; the consumer tool is deferred per the
  compaction RFC.

docs/cookbook/extension-cookbook.md

@@ -94,7 +94,7 @@ Every product feature maps to a listener on a documented extension seam — the
 | `/loop` | on the `turn/end` session event, `send()` the next iteration; or force-continue |
 | Dynamic workflow | orchestrator plugin on `turn/end` (or `step/end`) driving `send`/`steer` + subagents |
 | Queued + steering messages | core `Agent.send()` / `Agent.steer()` |
-| Context compaction (auto + manual) | the `ctx.compact` seam + a backend (`dsh-compact-basic`) on the serial `agent/pre-step` seam; auto = token-pressure check before each step; the manual `/compact` tool invokes the same routine ([compaction RFC](../rfc/implemented/feature/2026-06-18-compaction-capability-seam.md)) |
+| Context compaction (auto + manual) | the `ctx.compact` seam + a backend (`dsh-compact-basic`) on the serial `agent/pre-step` seam; auto = token-pressure check before each step; a manual trigger invokes the same `ctx.compact` routine ([compaction RFC](../rfc/implemented/feature/2026-06-18-compaction-capability-seam.md) — the model-facing `/compact` consumer tool is deferred) |
 | System prompt configurability | `ctx.systemPrompt.section()` with ordering |
 | AGENTS.md (root) | a section provider reading the file |
 | AGENTS.md (subdir, on-touch) + file-change notices | `agent.inject()` from a watcher / tool-result listener |