feat(hooks): dsh-hooks-claude + dsh-hooks-codex bridges (hooks stack PR-F)

The two bridge plugins that run a user's existing Claude Code / Codex hook
config on the harness's typed interception seams, built on the shared
dsh-hook-protocol library. A bridge is a faithfulness adapter, not a power
tool: anything it does a native cordis plugin does more powerfully — the
bridge exists only to run UNMODIFIED external hooks.

- dsh-hooks-claude: CC dialect. Seven hook points (SessionStart,
  UserPromptSubmit, PreToolUse, PostToolUse, Stop, SubagentStart,
  SubagentStop), CC per-event stdin payloads, env + ${CLAUDE_PLUGIN_ROOT}/
  ${CLAUDE_PROJECT_DIR} substitution, literal-or-regex matcher.
- dsh-hooks-codex: Codex dialect — a deliberate subset. Five hook points,
  always-regex matcher, snake_case payloads (turn_id/model, no trailing
  newline), no env/substitution, block-only decisions.

Both map the neutral merged outcome onto the seam's typed Decision and stamp
an explicit {kind:'plugin'} source on injected context (so it is never
mislabeled as a user prompt). Config parse-failure is contained; only command
hooks run. updatedInput is logged+warned (input rewrite deferred); the Stop
loop-guard is deferred (TODO).

Tests: per-file 100% — config-parse unit branches + per-seam mappings
end-to-end through the REAL loop + REAL bash + REAL shell scripts (scripted
mock model only) + a real-Loader export-shape guard. A keyless ACP snapshot
scenario (hook-prompt-block) proves a UserPromptSubmit hook blocks a prompt
end-to-end (rejected turn -> ACP cancelled, hook/* events in the log); a
with-key e2e (hooks.e2e.ts) proves a PreToolUse hook blocks real bash
(verified on disk). The snapshot normalizer now scrubs hook/result.durationMs.

RFC: docs/rfc/implemented/feature/2026-06-30-hook-bridges.md

examples/acp-agent/tests/snapshots/hook-prompt-block/input.json

@@ -0,0 +1,7 @@
+{
+  "steps": [
+    { "op": "initialize" },
+    { "op": "newSession" },
+    { "op": "prompt", "text": "Delete everything in the repo." }
+  ]
+}

examples/acp-agent/tests/snapshots/hook-prompt-block/session.jsonl

@@ -0,0 +1,5 @@
+{"type":"session","version":0,"id":"{{sessionId}}","createdAt":0,"cwd":"{{cwd}}"}
+{"type":"turn/start","seq":0,"time":0,"data":{"turn":1,"trigger":{"kind":"message","source":{"kind":"user"}}}}
+{"type":"hook/invoked","seq":1,"time":0,"data":{"turn":1,"point":"UserPromptSubmit","dialect":"claude","handlerId":"claude:UserPromptSubmit:1"}}
+{"type":"hook/result","seq":2,"time":0,"data":{"turn":1,"point":"UserPromptSubmit","handlerId":"claude:UserPromptSubmit:1","decision":"block","exitCode":2,"stderrSummary":"blocked by policy hook","durationMs":0}}
+{"type":"turn/end","seq":3,"time":0,"data":{"turn":1,"reason":{"kind":"rejected","reason":"blocked by policy hook"}}}

examples/acp-agent/tests/snapshots/hook-prompt-block/stdout.golden.jsonl

@@ -0,0 +1,3 @@
+{"jsonrpc":"2.0","id":1,"result":{"protocolVersion":1,"agentInfo":{"name":"deepseek-harness-acp","version":"0.0.1"},"agentCapabilities":{"loadSession":true,"promptCapabilities":{"image":false,"audio":false,"embeddedContext":false}},"authMethods":[]}}
+{"jsonrpc":"2.0","id":2,"result":{"sessionId":"{{sessionId}}"}}
+{"jsonrpc":"2.0","id":3,"result":{"stopReason":"cancelled"}}

examples/acp-agent/tests/snapshots/hook-prompt-block/workspace/hooks.json

@@ -0,0 +1,11 @@
+{
+  "hooks": {
+    "UserPromptSubmit": [
+      {
+        "hooks": [
+          { "type": "command", "command": "echo 'blocked by policy hook' >&2; exit 2" }
+        ]
+      }
+    ]
+  }
+}