Add self-contained Gitea Git service with PostgreSQL integration

- Implements complete Gitea Git service following rick-infra self-contained architecture
- Uses PostgreSQL infrastructure role as dependency and manages own database/user
- Native Arch Linux installation via pacman packages
- Automatic database setup (gitea database and user creation)
- SystemD service with security hardening and proper dependency management
- Caddy reverse proxy integration deployed to sites-enabled directory
- SSH server on port 2222 with automatic host key generation
- Production-ready with LFS support, security headers, and HTTPS via Caddy
- Follows simplified configuration approach with essential variables only
- Self-contained pattern: service manages complete setup independently

roles/gitea/defaults/main.yml

@@ -0,0 +1,76 @@
+---
+# =================================================================
+# Gitea Git Service Role - Simplified Configuration
+# =================================================================
+# Self-contained Gitea installation that manages its own database
+# Follows rick-infra patterns for pragmatic service deployment
+
+# =================================================================
+# Service Configuration
+# =================================================================
+
+# Service Management
+gitea_service_enabled: true
+gitea_service_state: "started"
+
+# User and Paths (Arch Linux defaults)
+gitea_user: "git" 
+gitea_group: "git"
+gitea_home: "/var/lib/gitea"
+
+# Network Configuration
+gitea_http_port: 3000
+gitea_ssh_port: 2222
+
+# =================================================================
+# Domain and Caddy Integration 
+# =================================================================
+
+# Domain setup (follows rick-infra pattern)
+gitea_subdomain: "git"
+gitea_domain: "{{ caddy_domain | default('localhost') }}"
+gitea_full_domain: "{{ gitea_subdomain }}.{{ gitea_domain }}"
+
+# Caddy integration
+caddy_sites_enabled_dir: "/etc/caddy/sites-enabled"
+
+# =================================================================
+# Database Configuration (Self-Contained)
+# =================================================================
+
+# Gitea manages its own database
+gitea_db_type: "postgres"
+gitea_db_host: "127.0.0.1"
+gitea_db_port: 5432
+gitea_db_name: "gitea"
+gitea_db_user: "gitea"
+gitea_db_password: "{{ vault_gitea_db_password }}"
+
+# =================================================================
+# Application Settings
+# =================================================================
+
+# Basic Gitea configuration
+gitea_app_name: "Gitea: Git with a cup of tea"
+gitea_run_mode: "prod"
+
+# Repository settings
+gitea_default_branch: "main"
+gitea_enable_lfs: true
+
+# Security settings
+gitea_disable_registration: false
+gitea_require_signin: false
+
+# SSH settings
+gitea_start_ssh_server: true
+
+# =================================================================
+# Rick-Infra Integration Notes
+# =================================================================
+# This role:
+# - Depends on PostgreSQL infrastructure role
+# - Creates its own database and user 
+# - Deploys Caddy configuration to sites-enabled
+# - Uses native Arch Linux Gitea package
+# - Follows self-contained service pattern