feat(omp): install omp in the docker agent image, isolate its credentials

OMP had full routing at the Docker layer (default pane command, schema) but
was never actually installed in docker/agent.Dockerfile, and had no
credential-isolation entry in docker-hosts.ts's CRED_STORES - a Docker-mode
OMP session would have failed with "omp: command not found", and even with
the binary present would have had no config/auth seeded, despite the README
already claiming OMP has "seamless auth, isolated credentials" in Docker.

- docker/agent.Dockerfile: install omp via its own installer (standalone
  binary, same shape as grok/antigravity - not on npm). Verified against a
  real --no-cache build: the installer actually targets ~/.local/bin, not
  ~/.omp/bin as the resolver's OMP_SEARCH_DIRS ordering would suggest -
  confirmed omp/18.0.8 installs and runs correctly inside the image.
- src/docker-hosts.ts: add a .omp/agent CRED_STORES entry. Unlike every
  sibling CLI in this family, sessions/ is SHARED (RW), not seeded: Codeman
  reads ~/.omp/agent/sessions/**/*.jsonl host-side for history recovery and
  --resume pinning (omp-transcript.ts, omp-session-resolver.ts), the same
  reason codex's sessions/ is shared rather than seeded. Seeding it instead
  would silently break the kill-survival feature for Docker cases. Only the
  small config files (config.yml/mcp.json/models.yml/settings.yml) are
  seeded; the SQLite caches and terminal-sessions/ stay container-local.
- test/docker-hosts.test.ts: pin the new CRED_STORES entry's behavior.

Found in passing (NOT fixed here, unrelated and pre-existing on master): the
agent image's DeepSeek (dsh) plugin-install step currently fails on a fresh
build ("pnpm not found on PATH"), confirmed via git diff against
origin/master that this line is untouched by this branch. Worth a separate
issue/PR.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/docker-hosts.ts

@@ -640,6 +640,22 @@ const CRED_STORES: CredStorePolicy[] = [
   },
   { rel: '.config/gcloud', seedWhole: true },
   { rel: '.config/opencode', seedWhole: true },
+  // OMP keeps its config in `~/.omp/agent` (config.yml/mcp.json/models.yml/
+  // settings.yml — small, no bigger than grok's config.toml/pager.toml), but
+  // that dir ALSO holds agent.db/history.db/models.db (SQLite caches) and
+  // terminal-sessions/blobs/cache (large, regenerable), so seed only the
+  // config files. UNLIKE pi/grok, `sessions/` is SHARED (RW), not
+  // host-invisible: Codeman reads `~/.omp/agent/sessions/**/*.jsonl`
+  // HOST-SIDE for history recovery and --resume pinning
+  // (omp-transcript.ts, omp-session-resolver.ts) — the same reason codex's
+  // `sessions/` is shared rather than seeded. Without this, an in-container
+  // OMP conversation would be invisible to Codeman's own history-scan/resume
+  // logic, silently breaking the kill-survival feature for Docker cases.
+  {
+    rel: '.omp/agent',
+    shareDirs: ['sessions'],
+    seedFiles: ['config.yml', 'mcp.json', 'models.yml', 'settings.yml'],
+  },
 ];
 
 /**