… uninstall

The helm deployer no longer emits undeploy.sh. Bundle teardown delegates to
the deployer-native uninstall path (helm uninstall, ArgoCD app deletion).

The script had accumulated complexity across multiple hardening passes
chasing CRD lifecycle, finalizer resolution, and multi-tenancy safety —
problems Helm itself deliberately avoids and that purpose-built deployers
handle more safely. AICR's role is to generate validated design-time
bundles, not to be the deployer.

Migration:

| Before                          | After (helm)                                  |
| ------------------------------- | --------------------------------------------- |
| ./undeploy.sh                   | helm uninstall <release> -n <namespace>       |
| ./undeploy.sh --delete-pvcs     | kubectl -n <ns> delete pvc --all              |
| ./undeploy.sh --keep-namespaces | (default; Helm doesn't delete namespaces)     |

| Before        | After (argocd / argocd-helm)                  |
| ------------- | --------------------------------------------- |
| ./undeploy.sh | kubectl -n argocd delete application <parent> |

See the new "Bundle Uninstall" section in docs/user/cli-reference.md for
full per-deployer walkthroughs, CRD/PVC handling, and stuck-release recovery.

Closes #671

…dback

Addresses three valid review concerns from @yuanchen8911 and matching
inline feedback from coderabbit:

1. README uninstall list missed auxiliary releases. The Uninstall block in
   the generated README.md ranged over recipe components, but deploy.sh
   installs every NNN-* folder including injected *-pre / *-post
   auxiliaries. Threaded localformat.Write's folder list through to the
   README template via a new releaseRef type; the template now enumerates
   every emitted release in reverse-install order. Verified
   testdata/mixed_with_pre and testdata/mixed_gpu_operator now include the
   *-pre / *-post releases. Folder gains a Namespace field so the caller
   doesn't have to re-derive it.

2. Stale undeploy.sh survived bundle regeneration. localformat.Write only
   prunes NNN-* folders; regenerating over a pre-PR bundle left an
   executable, unchecksummed undeploy.sh contradicting the new README.
   Generate() now explicitly removes any top-level undeploy.sh up front,
   ignoring ENOENT but propagating other errors. Covered by happy-path
   and error-path tests.

3. ArgoCD uninstall doc claimed AICR sets resources-finalizer on every
   Application — false; the argocd templates set no finalizer. Rewrote
   the argocd walkthrough to recommend `argocd app delete --cascade` or a
   manual `kubectl patch` to add the finalizer before delete. Also
   corrected the argocd-helm wording: ArgoCD with a Helm source uses
   helm template + native pruning, not `helm uninstall`. Added flux
   (HelmRelease delete) and helmfile (`helmfile destroy`) subsections so
   the section covers every deployer AICR generates.

Tests:
- New TestReverseReleases replaces TestReverseComponents (dead helper
  removed alongside its consumer).
- New TestGenerate_RemovesStaleUndeployScript +
  TestGenerate_StaleUndeployRemovalErrorPropagates lock in the
  stale-removal behavior on both paths.
- Regenerated 6 golden testdata bundles for the new README shape.

Coverage on pkg/bundler/deployer/helm: 84.2% (main) -> 84.0% (-0.2%).

…nd 2

Two follow-up nits from coderabbit on commit 125f49b:

1. `argocd app delete --cascade=foreground` is not valid CLI syntax;
   `--cascade` is a boolean and foreground propagation is set via
   `--propagation-policy`. Fixed both occurrences in
   docs/user/cli-reference.md (argocd + argocd-helm walkthroughs) to
   use `--cascade --propagation-policy foreground`.

2. README.md.tmpl emitted adjacent fenced code blocks without a blank
   line between them when the bundle has multiple releases (e.g.
   `mixed_with_pre`, `mixed_gpu_operator`), violating markdownlint
   MD031. Tightened the range body's whitespace control so each
   `helm uninstall` block is separated by exactly one blank line, with
   exactly one blank line between the final block and the next
   paragraph. Regenerated all 6 golden bundles.