docs(developer-guide): fix stale ISO-builder path and CLAUDE.md label

Verified the project-structure tree against the tree. Two stale entries:
- image-recipe/build-auto-installer-iso.sh was the old builder, now under
  _archived/; the current builder is image-recipe/build-debian-iso.sh (the
  release workflow drives it via scripts/build-iso-release.sh). Repointed.
- CLAUDE.md was labelled "AI development instructions"; it is now the sanitized
  public contributor guide. Relabelled.

Everything else verified: run-tests.sh, first-boot-containers.sh, container.rs,
vpn.rs all exist; the add-an-endpoint / add-a-Vue-page tutorials match the
current dispatch pattern.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/developer-guide.md

@@ -57,7 +57,7 @@ archy/
 │   ├── first-boot-containers.sh   # ISO first-boot setup
 │   └── run-tests.sh               # CI test runner
 ├── image-recipe/                  # ISO build configuration
-│   ├── build-auto-installer-iso.sh
+│   ├── build-debian-iso.sh
 │   └── configs/                   # Nginx, systemd configs
 ├── docs/                          # Documentation
 │   ├── architecture.md
@@ -65,7 +65,7 @@ archy/
 │   ├── marketplace-protocol.md
 │   └── multi-node-architecture.md
 ├── apps/                          # App manifests (YAML)
-├── CLAUDE.md                      # AI development instructions
+├── CLAUDE.md                      # Contributor guide (invariants, build/verify)
 └── docs/ROADMAP.md                # Project roadmap
 ```