docs: repair rewritten rationale and stale claims from the ACP reduction

The automation-only rewrite edited many implemented Agent Notes; several
edits replaced still-live or historical rationale instead of reframing:

- llm-model-catalog: restore the prompt/request consistency section and
  selection-ownership alternatives — installAgentLlmTarget and the TUI
  /model selector still ship that design; only the ACP wire is gone.
- plan-specific-collaboration-state, acp-multi-session, todo-write,
  ask-user-question: link the superseding automation-only note instead
  of silently rewriting the original decision or motivation; drop a
  paragraph duplicating the Web-provider facts stated two paragraphs up.
- sandbox: stop claiming unit coverage for turn-enclosed config writes
  (that mechanism left with the bridge) and retitle the commit-boundary
  paragraph accordingly.
- Fix the missing blank line before '## Consequences' in the
  plugin-command-registration pair, the JSON-RPC/Web render-intent
  consumer misattribution (the second consumer is the host/client
  runtime), stale bash_output/bash_kill names, and 'optional goals' in
  architecture.md.
- examples/acp-agent/README.md: point at the package contract instead
  of restating it; packages/ui/permission and plan-mode READMEs record
  the consumer-less preset service and the exit_plan_mode coverage gap
  under Known Limitations.
- 2026-06-19-acp-snapshot-tests: the new note defers the corpus
  migration rather than committing to it; say so.

Re-record the touched bilingual pairs.

.agents/notes/implemented/testing/2026-06-19-acp-snapshot-tests.md

@@ -77,6 +77,6 @@ Tool determinism comes from a generated cwd, scrubbed environment, fresh non-log
 
 ## Consequences
 
-The tier adds reviewed per-scenario input, session, stdout, optional override, and optional workspace fixtures. Workspace seeds are copied into the generated cwd for both record and replay. In return the tier provides deterministic keyless coverage through the real Loader and tool composition. Most retained scenarios exercise the assembled backend rather than ACP; the [automation-only ACP decision](../simplification/2026-07-23-acp-automation-only-protocol.md#snapshot-boundary) records the explicit follow-up to move that corpus to a transport-neutral headless suite.
+The tier adds reviewed per-scenario input, session, stdout, optional override, and optional workspace fixtures. Workspace seeds are copied into the generated cwd for both record and replay. In return the tier provides deterministic keyless coverage through the real Loader and tool composition. Most retained scenarios exercise the assembled backend rather than ACP; the [automation-only ACP decision](../simplification/2026-07-23-acp-automation-only-protocol.md#snapshot-boundary) keeps that corpus here and defers any move to a transport-neutral headless suite as an independent testing change (the suite-level FIXME marks it).
 
 This Agent Note relates to but does not supersede the [proposed determinism Agent Note](../../proposed/testing/2026-06-11-deterministic-and-stress-testing.md): that proposal's "universal replay fixture" re-derives session *message history* after every test (an internal-consistency invariant), whereas these snapshots pin assembled behavior plus the external automation output. They are complementary until the backend corpus moves off ACP.