Add Home Assistant MQTT auto-discovery integration

- Implement `Systant.HaDiscovery` module for automatic device registration
- Add comprehensive sensor discovery: CPU, memory, GPU, disk, network, temperature
- Update MQTT client to publish discovery messages on startup
- Add HomeAssistant configuration section to systant.toml
- Create example configuration file with localhost MQTT broker
- Update CLAUDE.md with complete HA integration documentation
- Add mosquitto to development dependencies for testing

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

server/systant.toml.example

@@ -0,0 +1,108 @@
+# Systant Configuration Example
+# Copy to systant.toml and customize for your environment
+
+[general]
+enabled_modules = ["cpu", "memory", "disk", "gpu", "network", "temperature", "processes", "system"]
+collection_interval = 30000  # milliseconds
+startup_delay = 5000        # milliseconds
+
+[mqtt]
+host = "localhost"          # MQTT broker hostname/IP
+port = 1883                 # MQTT broker port
+client_id_prefix = "systant" # Prefix for MQTT client ID
+username = ""               # MQTT username (optional)
+password = ""               # MQTT password (optional)
+qos = 0                     # MQTT QoS level
+
+# Home Assistant MQTT Discovery Configuration
+[homeassistant]
+discovery_enabled = true              # Enable/disable HA auto-discovery
+discovery_prefix = "homeassistant"    # HA discovery topic prefix
+
+[cpu]
+enabled = true
+
+[memory]
+enabled = true
+show_detailed = true
+
+[disk]
+enabled = true
+include_mounts = []                                     # Only include these mounts (empty = all)
+exclude_mounts = ["/snap", "/boot", "/dev", "/sys", "/proc", "/run", "/tmp"]
+exclude_types = ["tmpfs", "devtmpfs", "squashfs", "overlay"]
+min_usage_percent = 1                                   # Minimum usage to report
+
+[gpu]
+enabled = true
+nvidia_enabled = true
+amd_enabled = true
+max_gpus = 8
+
+[network]
+enabled = true
+include_interfaces = []                                 # Only include these interfaces (empty = all)
+exclude_interfaces = ["lo", "docker0", "br-", "veth", "virbr"]
+min_bytes_threshold = 1024                              # Minimum traffic to report
+
+[temperature]
+enabled = true
+cpu_temp_enabled = true
+sensors_enabled = true
+temp_unit = "celsius"
+
+[processes]
+enabled = true
+max_processes = 10
+sort_by = "cpu"                                         # "cpu" or "memory"
+min_cpu_percent = 0.0
+min_memory_percent = 0.0
+max_command_length = 50
+
+[system]
+enabled = true
+include_uptime = true
+include_load_average = true
+include_kernel_version = true
+include_os_info = true
+
+[commands]
+enabled = true
+timeout_seconds = 30
+log_executions = true
+
+# Example commands - customize for your needs
+[[commands.available]]
+trigger = "restart"
+command = "systemctl"
+allowed_params = ["nginx", "apache2", "docker", "ssh"]
+description = "Restart system services"
+
+[[commands.available]]
+trigger = "info"
+command = "uname"
+allowed_params = ["-a"]
+description = "Show system information"
+
+[[commands.available]]
+trigger = "df"
+command = "df"
+allowed_params = ["-h", "/", "/home", "/var", "/tmp"]
+description = "Show disk usage"
+
+[[commands.available]]
+trigger = "ps"
+command = "ps"
+allowed_params = ["aux", "--sort=-pcpu", "--sort=-pmem"]
+description = "Show running processes"
+
+[[commands.available]]
+trigger = "ping"
+command = "ping"
+allowed_params = ["-c", "4", "8.8.8.8", "google.com", "1.1.1.1"]
+description = "Network connectivity test"
+
+[logging]
+level = "info"                                          # debug, info, warn, error
+log_config_changes = true
+log_metric_collection = false