docs: give architecture review rules a per-artifact home

Move `docs/defensive-patterns.md` into `docs/defensive-patterns/`, one page per
artifact plus a README router, and state each rule as its requirement, the
condition a reviewer judges it by, its boundary and approver, and a correct and
a wrong example.

- `general.md` (the moved page): the existing bug-class rules plus timing,
  value representation, shared-state ownership, decentralization, performance
  evidence, and migrations.
- `package-surface.md`, `remote-and-api.md`, `client-components.md`,
  `conversation-and-session.md`: the review requirements for those artifacts,
  linking type definitions and semantics to `docs/subsystems/` instead of
  restating them.
- `README.md`: the habits behind the rules and the route from artifact to page.
- `dsh-code-review` reads the owning pages before judging a diff; the
  `dsh-architecture-discipline` routing skill is retired in favour of the
  directory, and every inbound reference is repaired.
- Chinese counterparts, pairing records, and the documentation tier table are
  updated together.

packages/experimental/ptc-runtime-python/src/index.ts

@@ -1124,7 +1124,7 @@ export class PythonPtcRuntime extends PtcRuntime {
       // child can dispatch. `namespace.functions` is caller-supplied, so it may
       // expose members through getters or a Proxy; reading one of them inside
       // the fd-3 `data` callback would throw OUTSIDE the dispatcher's try and
-      // terminate the host (defensive-patterns contain-callback-exceptions).
+      // terminate the host (docs/defensive-patterns/general.md contain-callback-exceptions).
       // Reading every member here, in run()'s synchronous validation segment,
       // turns that throw into the seam-misuse rejection run() reserves for
       // malformed bindings. The snapshot is also the single key set the boot