feat: add developer container config with packages/ mount

- docker-compose.yml for standalone Docker usage
- .devcontainer/devcontainer.json for VS Code/Cursor
- Mounts packages/ as /workspace in container
- Persists home directory with named volume
- SSH and gitconfig mounted read-only

Uses ghcr.io/host-uk/core-images/developer:latest

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.devcontainer/devcontainer.json

@@ -0,0 +1,33 @@
+{
+  "name": "Core Developer",
+  "image": "ghcr.io/host-uk/core-images/developer:latest",
+  
+  "workspaceMount": "source=${localWorkspaceFolder}/packages,target=/workspace,type=bind",
+  "workspaceFolder": "/workspace",
+  
+  "mounts": [
+    "source=${localEnv:HOME}/.ssh,target=/root/.ssh,type=bind,readonly",
+    "source=${localEnv:HOME}/.gitconfig,target=/root/.gitconfig,type=bind,readonly",
+    "source=core-dev-home,target=/root,type=volume"
+  ],
+  
+  "containerEnv": {
+    "TERM": "xterm-256color",
+    "EDITOR": "nvim"
+  },
+  
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "bmewburn.vscode-intelephense-client",
+        "golang.go",
+        "ms-python.python",
+        "rust-lang.rust-analyzer"
+      ]
+    }
+  },
+  
+  "postCreateCommand": "echo 'Core Developer ready. Workspace: /workspace (packages/)'",
+  
+  "remoteUser": "root"
+}

docker-compose.yml

@@ -0,0 +1,29 @@
+# Core Developer Environment
+# Mounts packages/ as /workspace in the container
+
+services:
+  dev:
+    image: ghcr.io/host-uk/core-images/developer:latest
+    container_name: core-dev
+    hostname: core-dev
+    stdin_open: true
+    tty: true
+    volumes:
+      # Mount packages directory as workspace
+      - ./packages:/workspace
+      # Persist home directory configs
+      - dev-home:/root
+      # SSH keys for git operations
+      - ~/.ssh:/root/.ssh:ro
+      # Git config
+      - ~/.gitconfig:/root/.gitconfig:ro
+    environment:
+      - TERM=xterm-256color
+      - EDITOR=nvim
+    working_dir: /workspace
+    # Keep container running
+    command: ["/bin/zsh"]
+
+volumes:
+  dev-home:
+    name: core-dev-home