docs: rewrite README with structured overview and quick start guide

Replaces the minimal project description with a comprehensive README
including a component overview table, quick start instructions, common
Ansible operations, and links to detailed documentation. Aligns with
Red Panda Approval™ standards.

ansible/casdoor/docker-compose.yml.j2

@@ -0,0 +1,34 @@
+# -----------------------------------------------------------------------------
+# Casdoor Docker Compose
+# -----------------------------------------------------------------------------
+# Casdoor SSO - connects to native PostgreSQL on localhost
+# Generated by Ansible - do not edit manually
+# -----------------------------------------------------------------------------
+
+services:
+  # ---------------------------------------------------------------------------
+  # Casdoor - SSO Identity Provider
+  # ---------------------------------------------------------------------------
+  casdoor:
+    image: casbin/casdoor:latest
+    pull_policy: always
+    container_name: casdoor
+    network_mode: host  # Access localhost PostgreSQL directly
+    environment:
+      RUNNING_IN_DOCKER: "true"
+    user: "{{ casdoor_uid }}:{{ casdoor_gid }}"
+    volumes:
+      - ./conf:/conf:ro
+    logging:
+      driver: syslog
+      options:
+        syslog-address: "tcp://127.0.0.1:{{ casdoor_syslog_port }}"
+        syslog-format: "{{ syslog_format | default('rfc3164') }}"
+        tag: "casdoor"
+    restart: unless-stopped
+    healthcheck:
+      test: ["CMD", "wget", "-q", "--spider", "http://localhost:{{ casdoor_port }}/api/health"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 60s