fix(docker): make the dsh profile install survive pnpm's build-script gate

Follow-up to #350, which fixed the actual blocker (issue #352): `dsh plugin` is
a thin forwarder that `spawnSync`s a literal `pnpm` with no npm fallback, so an
image without pnpm dies at exit 127 and takes the whole build with it.

That PR also pinned an allowlist of the two packages whose lifecycle scripts
pnpm blocked at the time. Replace it with a policy that cannot go stale: pnpm,
unlike npm, refuses dependency build scripts by default and FAILS the install
over it (`ERR_PNPM_IGNORED_BUILDS`, exit 1, measured on pnpm 11.24), and the
names to allow move between rebuilds because `@deepseek-harness-tui/dsh-tui` is
resolved by dist-tag, not pinned: 0.9.3 pulled `@google/genai` (whose script is
a literal `preinstall: no-op`), 0.10.0-beta.x does not. An allowlist of two
names would have let the next tree break the build the same way. Allowing them
wholesale is also the exposure this image already accepts three layers up,
where `npm install -g` runs the install scripts of every transitive dep of the
five CLIs above with no gate at all.

Also correct a comment in the `/api/deepseek/install-profile` route that
asserted the opposite of what #352 proved ("dsh bundles its own package
manager, so no system pnpm is required"). The route's behavior is already
right: dsh's own "pnpm not found on PATH" stderr reaches the caller as the
OPERATION_FAILED detail, so the UI's "add a terminal profile" button names the
fix. Documented the prerequisite in docs/deepseek-integration.md, and taught
the docker-cases image smoke test about `dsh`/`omp` plus the profile check that
`dsh --version` does NOT cover.

docs/deepseek-integration.md

@@ -47,6 +47,14 @@ By hand, or to pick a different front door:
 dsh plugin --profile dsh-tui add @deepseek-harness-tui/dsh-tui
 ```
 
+⚠️ **`pnpm` has to be on PATH for either route.** `dsh plugin` is a thin forwarder
+that spawns a literal `pnpm` with no npm fallback, so without one it exits 127 with
+`dsh: pnpm not found on PATH` — both by hand and behind the UI button, which
+surfaces that same line as the install error. `npm install -g pnpm` (or
+`corepack enable pnpm`) is the fix. This is what broke the Docker agent image in
+[#352](https://github.com/Ark0N/Codeman/issues/352); the image now installs pnpm
+alongside `dsh`.
+
 Codeman's default is `@deepseek-harness-tui/dsh-tui` because it is by a wide
 margin the most used community TUI, it is MIT, and it implements the status
 contract described in §3. It is a **default, not a requirement**: any profile