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/prometheus/alertmanager.yml

@@ -0,0 +1,92 @@
+lobal:
+  resolve_timeout: 5m
+
+route:
+  group_by: ['alertname', 'instance', 'severity']
+  group_wait: 30s
+  group_interval: 5m
+  repeat_interval: 4h
+  receiver: 'pushover'
+  routes:
+  - match:
+      severity: critical
+    receiver: 'pushover-critical'
+    continue: true
+  - match:
+      severity: warning
+    receiver: 'pushover-warning'
+    continue: true
+  - match:
+      severity: info
+    receiver: 'pushover-info'
+    repeat_interval: 24h
+
+inhibit_rules:
+  - source_match:
+      severity: 'critical'
+    target_match:
+      severity: 'warning'
+    equal: ['alertname', 'instance']
+
+receivers:
+- name: 'pushover-critical'
+  pushover_configs:
+  - user_key: '{{ pushover_user_key }}'
+    token: '{{ pushover_api_token }}'
+    send_resolved: true
+    html: true
+    priority: '2'  # Emergency priority
+    retry: 30
+    expire: 3600
+    title: '🚨 [CRITICAL] {{ "{{" }} .GroupLabels.alertname {{ "}}" }}'
+    message: |-
+      {{ "{{" }} range .Alerts {{ "}}" }}
+      {{ "{{" }} .Annotations.description {{ "}}" }}
+      
+      Instance: {{ "{{" }} .Labels.instance {{ "}}" }}
+      {{ "{{" }} end {{ "}}" }}
+
+- name: 'pushover-warning'
+  pushover_configs:
+  - user_key: '{{ pushover_user_key }}'
+    token: '{{ pushover_api_token }}'
+    send_resolved: true
+    html: true
+    priority: '1'  # High priority
+    retry: 30
+    expire: 3600
+    title: '⚠️ [WARNING] {{ "{{" }} .GroupLabels.alertname {{ "}}" }}'
+    message: |-
+      {{ "{{" }} range .Alerts {{ "}}" }}
+      {{ "{{" }} .Annotations.description {{ "}}" }}
+      
+      Instance: {{ "{{" }} .Labels.instance {{ "}}" }}
+      {{ "{{" }} end {{ "}}" }}
+
+- name: 'pushover-info'
+  pushover_configs:
+  - user_key: '{{ pushover_user_key }}'
+    token: '{{ pushover_api_token }}'
+    send_resolved: false
+    html: true
+    priority: '0'  # Normal priority
+    title: '{{ "{{" }} .GroupLabels.alertname {{ "}}" }}'
+    message: '{{ "{{" }} range .Alerts {{ "}}" }}{{ "{{" }} .Annotations.description {{ "}}" }}{{ "{{" }} end {{ "}}" }}'
+
+- name: 'pushover'
+  pushover_configs:
+  - user_key: '{{ pushover_user_key }}'
+    token: '{{ pushover_api_token }}'
+    send_resolved: true
+    html: true
+    priority: '1'
+    retry: 30
+    expire: 3600
+    title: '[{{ "{{" }} .GroupLabels.severity | default "ALERT" {{ "}}" }}] {{ "{{" }} .GroupLabels.alertname {{ "}}" }}'
+    message: |-
+      {{ "{{" }} range .Alerts {{ "}}" }}
+      {{ "{{" }} .Annotations.description {{ "}}" }}
+      
+      Instance: {{ "{{" }} .Labels.instance {{ "}}" }}
+      Severity: {{ "{{" }} .Labels.severity {{ "}}" }}
+      {{ "{{" }} end {{ "}}" }}