Merge remote-tracking branch 'origin/master' into feat/plan-mode

Master arrivals re-grafted onto the plan-mode surfaces:
- Package invariant runtime contracts: every package owns ./invariant —
  added the dsh-mode companion (mode/set payload validation: non-empty
  trimmed name), its unit spec, exports/peer wiring, and the mode group in
  the tsconfig invariant paths glob.
- Interception waterfalls gained an AbortSignal parameter
  (agent/prompt-submit, agent/turn-continuation) and ToolExecutionInput.signal
  became required: listeners and test dispatch updated; the exit tool now
  forwards exec.signal unconditionally.
- TUI question dialog: master's position/unanswered header layout kept,
  the plan-review detail block re-grafted between question and answers.
- LSP capability family arrived: lsp tool joins the catalog pin, dsh-lsp
  examples deps beside dsh-mode; lsp-definition snapshot refreshed with
  the mode command and modes advertisement.
- docs/architecture.md and packages/README.md regenerated tables re-grafted
  (ctx.modes row, mode package row) and condensed within word ceilings.
- examples/acp-agent cordis.yml: kept the deployment-owned plan instructions
  (incl. the conversational-agreement sentence) beside master's routed-model
  compaction comment; snapshot expected outputs refreshed keyless and noise
  fixtures restored.

packages/support/acp-snapshot/src/invariant.ts

@@ -0,0 +1,30 @@
+/**
+ * Package-owned invariant companion for `@deepseek-ai/dsh-acp-snapshot`.
+ * @module @deepseek-ai/dsh-acp-snapshot/invariant
+ */
+
+/* jscpd:ignore-start */
+import type { Context } from 'cordis'
+import type { InvariantInstaller } from '@deepseek-ai/dsh-invariants'
+
+const PACKAGE_NAME = '@deepseek-ai/dsh-acp-snapshot'
+
+/** Cordis companion plugin name. */
+export const name = 'acp-snapshot-invariant'
+/** Service required before the companion can reserve package ownership. */
+export const inject = ['invariants']
+
+/**
+ * No runtime invariant: this test-support package owns no production event stream or mutable data;
+ * consuming test suites exercise its behavior.
+ */
+const install: InvariantInstaller = () => {}
+
+/**
+ * Register this package's invariant companion.
+ * @param ctx - Cordis context carrying the invariant service.
+ * @returns the installed registration's disposer after setup succeeds.
+ */
+export const apply = (ctx: Context): Promise<() => void> =>
+  Promise.resolve(ctx.invariants.register(PACKAGE_NAME, install))
+/* jscpd:ignore-end */