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.

scripts/doc-budgets.manifest.json

@@ -1,10 +1,9 @@
 {
   "AGENTS.md": 1960,
-  "docs/AGENTS.md": 1320,
+  "docs/AGENTS.md": 1430,
   "docs/architecture.md": 2410,
   "docs/cordis-primer.md": 600,
-  "docs/defensive-patterns.md": 550,
   "docs/testing.md": 1350,
-  "packages/AGENTS.md": 750,
+  "packages/AGENTS.md": 810,
   "packages/README.md": 994
 }