This commit centralizes common logic into the `core` module and refactors the `NodeDetailViewModel` and `MetricsViewModel` for clarity and efficiency.

Helper functions for validating metrics and signals have been moved to `core/model/util/Extensions.kt` for reuse. The logic for determining the effective node ID for log queries (mapping the local node number to 0) has been extracted into `NodeRepository`.

The `NodeDetailViewModel` is significantly refactored to simplify its complex data flow. The previous large `combine` operation with many arguments has been broken down into smaller, more manageable data groups for logs, identity, and metadata. This improves readability and maintainability.

Specific changes include:
- **`core/model`**:
    - Moved `hasValidEnvironmentMetrics` and a refined `isDirectSignal` (previously `hasValidSignal`) to `Extensions.kt`.
- **`core/data`**:
    - Added `effectiveLogNodeId` to `NodeRepository` to abstract the logic for determining which node ID to use for log lookups.
- **`feature/node`**:
    - **`MetricsViewModel`**: Updated to use the new centralized helper functions and the `effectiveLogNodeId` method from `NodeRepository`.
    - **`NodeDetailViewModel`**:
        - Refactored the `uiState` flow to use smaller, grouped `combine` calls for better organization.
        - Introduced internal data classes (`LogsGroup`, `IdentityGroup`, `MetadataGroup`) to structure the data fetching process.
        - Removed the large, monolithic `NodeDetailUiStateData` data class.
        - Adopted the new centralized helper and repository methods.

Signed-off-by: James Rich <2199651+jamesarich@users.noreply.github.com>

This commit refactors the `PositionSection` to conditionally display action buttons based on whether the node is local and has a valid position.

- The "Exchange Position" button is now only shown for remote nodes.
- For local nodes, the "Compass" button will now span the full width of the screen, but only if the node has a valid position.
- If the node is local and has no valid position, no action buttons are displayed.

Signed-off-by: James Rich <2199651+jamesarich@users.noreply.github.com>

This commit refactors data-fetching logic to centralize the mapping of the local node's number to a stable identifier (`MeshLog.NODE_NUM_LOCAL`), ensuring log continuity even if the local node ID changes.

The `MeshLogRepository` now transparently handles this redirection for all queries (`getTelemetryFrom`, `getLogsFrom`, `getMeshPacketsFrom`), removing this responsibility from the ViewModels. This simplifies the presentation layer by eliminating the need to resolve the `effectiveLogNodeId` before making a data request.

**Specific Changes:**
- **`MeshLogRepository`**:
    - Introduced a private `effectiveLogId` flow that maps the current node number to `MeshLog.NODE_NUM_LOCAL` if it's the local node.
    - All public data-fetching methods for a specific `nodeNum` now use this `effectiveLogId` flow internally.
    - Added documentation for public methods.
- **`NodeRepository`**:
    - Removed `effectiveLogNodeId` as its logic is now encapsulated within `MeshLogRepository`.
- **`MetricsViewModel` & `NodeDetailViewModel`**:
    - Removed all usage of `flatMapLatest` with `effectiveLogNodeId`.
    - Data flows are now fetched directly using the target `nodeNum`, relying on the repository to handle local node mapping.
- **`MeshLogDao`**:
    - Updated the query for `getLogsFrom` to use `-1` as a wildcard for `portNum`, improving clarity over the previous use of `0`.
- **Documentation**:
    - Added KDoc to `MeshLog`, `Node`, `MetricsViewModel`, `NodeDetailViewModel`, `NodeRepository`, and `MeshLogRepository` for better code clarity.

Signed-off-by: James Rich <2199651+jamesarich@users.noreply.github.com>

This commit prevents telemetry and paxcount packets that are requests for data (`want_response = true`) from being logged as data points in the metrics screen. This ensures that only actual measurement data is used for graphing and analysis.

Additionally, this change includes a minor bug fix in the position CSV export and general code reformatting.

Specific changes:
- Updated `MeshLogRepository` to filter out telemetry packets where `want_response` is true.
- Modified `MetricsViewModel` to ignore paxcounter packets where `want_response` is true.
- Corrected a variable name from `satsIn_view` to `satsInView` in the `savePositionCSV` function.
- Applied general code cleanup and reformatting across `MetricsViewModel.kt` and `MeshLogRepository.kt`.

Signed-off-by: James Rich <2199651+jamesarich@users.noreply.github.com>