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/argos/docker-compose.yml.j2

@@ -0,0 +1,44 @@
+services:
+  argos-searxng:
+    build: .
+    depends_on:
+      - kvdb
+    environment:
+      - ARGOS_PORT=8000
+      - ARGOS_HOST=0.0.0.0
+      - ARGOS_SEARXNG_INSTANCES={{argos_searxng_instances}}
+      - ARGOS_MEMCACHED_HOST=kvdb
+      - ARGOS_MEMCACHED_PORT=11211
+      - ARGOS_CACHE_TTL={{argos_cache_ttl}}
+      - ARGOS_MAX_RESULTS_DEFAULT={{argos_max_results}}
+      - ARGOS_REQUEST_TIMEOUT=30.0
+      - ARGOS_HEALTH_CHECK_TIMEOUT=5.0
+      - ARGOS_LOG_LEVEL={{argos_log_level}}
+      - ARGOS_ENABLE_STARTUP_HEALTH_CHECK=true
+    healthcheck:
+      test: ["CMD", "curl", "-f", "http://localhost:8000/live"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 40s
+    logging:
+      driver: syslog
+      options:
+        syslog-address: "tcp://127.0.0.1:{{argos_syslog_port}}"
+        syslog-format: "{{syslog_format}}"
+        tag: "athena-kvdb"
+    ports:
+      - {{argos_port}}:8000
+    restart: unless-stopped
+
+  kvdb:
+    image: memcached:1.6-trixie
+    pull_policy: always
+    command: memcached -m 128 -I 10m
+    logging:
+      driver: syslog
+      options:
+        syslog-address: "tcp://127.0.0.1:{{argos_syslog_port}}"
+        syslog-format: "{{syslog_format}}"
+        tag: "argos-kvdb"
+    restart: unless-stopped