Add web setup UI for first-boot config

- server.py: Flask-free Python web server on port 80
  - 4-step wizard: network → tier → tools → live install log
  - DHCP or static IP support
  - SSE log streaming, handles phase-1 reboot gracefully
- user-data: deploy web UI service instead of TUI (whiptail)
  - sets hostname to cezenai (accessible as cezenai.local)
  - installs python3, avahi-daemon
- entry.yml: skip roles based on skip_roles var from web UI
- install.sh: reads /opt/cezen/install.conf for tier & skip_roles

ansible/entry.yml

@@ -10,15 +10,26 @@
     cezen_home: "/opt/cezen"
     python_version: "3.11"
     cuda_version: "12.4"
+    skip_roles: ""   # comma-separated list of role names to skip (set by install.sh)
 
   roles:
-    - base
-    - docker
-    - k3s
-    - ollama
-    - vllm
-    - jupyterlab
-    - chromadb
-    - mlflow
-    - minio
-    - monitoring
+    - role: base
+      when: "'base' not in skip_roles.split(',')"
+    - role: docker
+      when: "'docker' not in skip_roles.split(',')"
+    - role: k3s
+      when: "'k3s' not in skip_roles.split(',')"
+    - role: ollama
+      when: "'ollama' not in skip_roles.split(',')"
+    - role: vllm
+      when: "'vllm' not in skip_roles.split(',')"
+    - role: jupyterlab
+      when: "'jupyterlab' not in skip_roles.split(',')"
+    - role: chromadb
+      when: "'chromadb' not in skip_roles.split(',')"
+    - role: mlflow
+      when: "'mlflow' not in skip_roles.split(',')"
+    - role: minio
+      when: "'minio' not in skip_roles.split(',')"
+    - role: monitoring
+      when: "'monitoring' not in skip_roles.split(',')"