feat: add IDE choice — VSCode (default), Google Antigravity, SSH

- Add `ide` Helm value with options: vscode, antigravity, ssh
- Dockerfile: install Google Antigravity via apt and openssh-server
- scripts/startapp.sh: branch on IDE env var to launch the right app
- scripts/cont-init-sshd.sh: start sshd as root in SSH mode, set up
  authorized_keys from SSH_AUTHORIZED_KEYS env var
- chart/templates/deployment.yaml: pass IDE env var, conditional ports
  and probes (HTTP for VNC modes, TCP socket for SSH mode)
- chart/templates/service.yaml: expose port 5800 (VNC) or 22 (SSH)
- chart/values.yaml: add ide field with documentation
- README.md: document IDE choice, fix stale happyHomeDir references
- chart/Chart.yaml: bump to 0.1.5

Closes #10

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

chart/values.yaml

@@ -9,6 +9,14 @@ image:
 # GitHub repository to clone into /workspace
 githubRepo: ""
 
+# IDE to launch inside the container.
+# Options:
+#   vscode      — VSCode via VNC browser UI on port 5800 (default)
+#   antigravity — Google Antigravity (VSCode fork) via VNC on port 5800
+#   ssh         — OpenSSH server on port 22 (no VNC GUI)
+#                 Requires SSH_AUTHORIZED_KEYS in the env secret.
+ide: vscode
+
 # Happy Coder endpoints
 happyServerUrl: "https://happy.farh.net"
 happyWebappUrl: "https://happy-coder.farh.net"