feat: issues/1597: Temperature Monitoring - Thanks @MitchellThompkins

# Temperature Monitoring System

## Description
This PR implements a comprehensive temperature monitoring system
integrated into the existing `MetricsResolver`. It provides real-time
access to temperature data from various system sensors via GraphQL
queries and subscriptions.

I tested these changes locally using the provided Apollo Server on
Unraid `7.2.0`.

Addresses [#1597](#1597)

## Key Features
*   **Multi-Source Support:**
    *   **CPU & Motherboard:** Via `lm-sensors` integration.
    *   **Disks:** Modifies `smartctl` integration
* Modifies `smartctl` to leverage json parsing instead of raw strings.
    *   **IPMI:** Support for `ipmitool` sensors (see notes below!).
*   **GraphQL API:**
    *   New `temperature` field on the `Metrics` node.
    *   `systemMetricsTemperature` subscription for real-time updates.
    *   Exposes `current`, `min`, `max`, and `history` for each sensor.
*   **Configuration:**
* Fully configurable via `api.json` (enabled status, polling intervals,
thresholds).
* Support for `default_unit` preference (Celsius/Fahrenheit) with
automatic conversion.
*   **History & Aggregation:**
    *   In-memory history tracking with configurable retention.
* Summary statistics (average temp, hottest/coolest sensor counts).

## Implementation Details
* **Binary Management:** Relies on system-installed tools (`sensors`,
`smartctl`, `ipmitool`) rather than bundling binaries, aligning with the
base OS integration strategy. **There is no attempt here to package
sensor tooling as part of this feature.** This is per a [conversation on
the feature scope with the Unraid
team](#1597 (comment)).
* **Architecture:** Implemented a modular `TemperatureSensorProvider`
interface allowing for easy addition of new sensor types.
* **Robustness:** `DisksService` was updated to parse `smartctl` JSON
output directly, resolving issues with raw string parsing on certain
drive models. There was an issue with some Seagate drives reporting raw
values with extra data in parentheses: `24 (0 14 0 0 0)`. Parsing the
last value in the string returned incorrect data. Parsing with json
prevents this.
*  **Testing:** Added unit tests for all additional modules.

## Documentation
* Added developer documentation at `docs/developer/temperature.md`
detailing configuration options and API usage.

## Scope Notes
* **IPMI Integration:** The `IpmiSensorsService` has been implemented to
parse standard `ipmitool` output, but **it has not been tested on live
hardware** as I do not have access to a system with IPMI support. It
relies on standard `ipmitool` output formats (at least the documentation
I saw and what AI told me).
* **GPU:** GPU temperature monitoring is currently out of scope and has
not been implemented. I do not have access to a machine with a GPU and
could not reliably test it.
* **Alerts:** The API calculates and exposes `WARNING` and `CRITICAL`
statuses based on thresholds but does not currently trigger active
system notifications. This type of alert is passive only.

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

## New Features
* Added comprehensive temperature monitoring with real-time metrics for
CPU, disk, and system sensors
* Configurable temperature thresholds and alerts (Warning/Critical
states)
* Support for multiple temperature units (Celsius, Fahrenheit, Kelvin,
Rankine)
* Temperature history tracking and trend analysis capability
* Real-time temperature metric subscriptions
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: MitchellThompkins

api/README.md

@@ -84,6 +84,7 @@ For detailed information about specific features:
 - [Feature Flags](docs/developer/feature-flags.md) - Conditionally enabling functionality
 - [Repository Organization](docs/developer/repo-organization.md) - Codebase structure
 - [Development Workflows](docs/developer/workflows.md) - Development processes
+- [Temperature Monitoring](docs/developer/temperature.md) - Configuration and API details for temperature sensors
 
 ## License
 

api/docs/developer/temperature.md

@@ -0,0 +1,144 @@
+# Temperature Monitoring
+
+The Temperature Monitoring feature allows the Unraid API to collect and expose temperature metrics from various sensors (CPU, Disks, Motherboard, etc.).
+
+## Configuration
+
+You can configure the temperature monitoring behavior in your `api.json`.
+Nominally the `api.json` file is found at
+`/boot/config/plugins/dynamix.my.servers/configs/`.
+
+### `api.temperature` Object
+
+| Key | Type | Default | Description |
+| :--- | :--- | :--- | :--- |
+| `enabled` | `boolean` | `true` | Globally enable or disable temperature monitoring. |
+| `default_unit` | `string` | `"celsius"` | The unit to return values in. Options: `"celsius"`, `"fahrenheit"`, `"kelvin"`, `"rankine"`. |
+| `polling_interval` | `number` | `5000` | Polling interval in milliseconds for the subscription. |
+| `history.max_readings` | `number` | `1000` | (Internal) Number of historical data points to keep in memory per sensor. |
+| `history.retention_ms` | `number` | `86400000` | (Internal) Retention period for historical data in milliseconds. |
+
+### `api.temperature.sensors` Object
+
+Enable or disable specific sensor providers.
+
+| Key | Type | Default | Description |
+| :--- | :--- | :--- | :--- |
+| `lm_sensors.enabled` | `boolean` | `true` | Enable `lm-sensors` provider (requires `sensors` binary). |
+| `lm_sensors.config_path` | `string` | `""` | Optional path to a specific sensors config file (passed as `-c` to `sensors`). |
+| `smartctl.enabled` | `boolean` | `true` | Enable disk temperature monitoring via `smartctl` (via DiskService). |
+| `ipmi.enabled` | `boolean` | `true` | Enable IPMI sensor provider (requires `ipmitool`). |
+| `ipmi.args` | `string[]` | `[]` | Optional array of arguments to pass to the `ipmitool` command. |
+
+### `api.temperature.thresholds` Object
+
+Customize warning and critical thresholds.
+
+| Key | Type | Default | Description |
+| :--- | :--- | :--- | :--- |
+| `warning` | `number` | `80` | Global warning threshold for other sensors. |
+| `critical` | `number` | `90` | Global critical threshold for other sensors. |
+| `cpu_warning` | `number` | `70` | Warning threshold for CPU. |
+| `cpu_critical` | `number` | `85` | Critical threshold for CPU. |
+| `disk_warning` | `number` | `50` | Warning threshold for Disks. |
+| `disk_critical` | `number` | `60` | Critical threshold for Disks. |
+
+### Sample Configuration
+
+Example of an `api.json` configuration file:
+
+```json
+{
+  "version": "4.28.2+9196778e",
+  "extraOrigins": [],
+  "sandbox": true,
+  "ssoSubIds": [],
+  "plugins": [
+    "unraid-api-plugin-connect"
+  ],
+  "temperature": {
+    "enabled": true,
+    "polling_interval": 10000,
+    "default_unit": "celsius",
+    "history": {
+      "max_readings": 144,
+      "retention_ms": 86400000
+    },
+    "thresholds": {
+      "cpu_warning": 75,
+      "cpu_critical": 90,
+      "disk_warning": 50,
+      "disk_critical": 60
+    },
+    "sensors": {
+      "lm_sensors": {
+        "enabled": true,
+        "config_path": "/etc/sensors3.conf"
+      },
+      "smartctl": {
+        "enabled": true
+      },
+      "ipmi": {
+        "enabled": false
+      }
+    }
+  }
+}
+```
+
+## GraphQL API
+
+### Query: `metrics` -> `temperature`
+
+Returns a snapshot of the current temperature metrics.
+
+```graphql
+query {
+  metrics {
+    temperature {
+      id
+      summary {
+        average
+        hottest {
+          name
+          current { value unit }
+        }
+      }
+      sensors {
+        id
+        name
+        type
+        current {
+          value
+          unit
+          status
+        }
+        history {
+          value
+          timestamp
+        }
+      }
+    }
+  }
+}
+```
+
+### Subscription: `systemMetricsTemperature`
+
+Subscribes to temperature updates (pushed at `polling_interval`).
+
+```graphql
+subscription {
+  systemMetricsTemperature {
+    summary {
+      average
+    }
+    sensors {
+      name
+      current {
+        value
+      }
+    }
+  }
+}
+```