This commit introduces a suite of new unit and instrumentation tests across various modules, significantly improving test coverage and code stability. It also includes several related bug fixes and minor refactorings identified during test creation.

### Key Changes:

-   **Test Suite Expansion:**
    -   **Service Layer (`app` module):**
        -   `MeshCommandSender`: Validates that a default hop limit of 3 is used when the device's configured limit is 0.
        -   `MeshConnectionManager`: Tests connection state transitions, including handling of `DeviceSleep` state with and without power saving enabled.
        -   `MeshMessageProcessor`: Verifies that incoming packets are buffered when the node database is not ready and flushed correctly once it becomes available.
        -   `FromRadioPacketHandler`: Ensures correct routing of `FromRadio` packets (`MyInfo`, `Metadata`, `NodeInfo`, etc.) to the appropriate handlers.
        -   `PacketHandler`: Tests packet queuing and sending logic based on connection state.
        -   `MeshNodeManager`: Refactored tests to use mocks, covering scenarios like preserving user details on incoming default user data.
        -   `MeshDataMapper`: Improved tests for mapping protobuf `MeshPacket` to the app's `DataPacket` model.
    -   **Radio Interfaces (`app` module):**
        -   `StreamInterface`: Added tests for byte stream parsing logic, covering various packet sizes and error conditions.
        -   `TCPInterface`: Added a test to verify correct heartbeat packet generation.
    -   **Core & Feature Modules:**
        -   `MeshLogRepository` (`core/data`): Added tests to confirm that a temperature value of `0.0` is correctly preserved and not treated as a missing value.
        -   `MetricsViewModel` (`feature/node`): Added tests for environment metrics filtering and state calculation.
        -   `BleOtaTransport` (`feature/firmware`): Verifies that the MTU is requested upon connection.

-   **Bug Fixes & Refinements:**
    -   **Hop Limit:** `MeshCommandSender` now enforces a default hop limit of `3` if the device's configuration is `0`, preventing packets from being dropped immediately.
    -   **Temperature Display:**
        -   The `MetricsViewModel` now correctly respects the global `IMPERIAL` display unit for showing temperature in Fahrenheit, in addition to the specific module setting.
        -   Fixed a bug where a valid temperature of `0.0` was not being displayed; it is now correctly handled as a valid metric and not filtered out as `NaN`.
    -   **QR Code UI:**
        -   When adding new channels via a QR code (not replacing), existing channels are now correctly preserved and visually disabled in the selection dialog.
        -   Added more descriptive text to the QR code dialog to clarify the difference between adding channels and replacing the entire configuration.

-   **Build & Dependency Management:**
    -   Added `Robolectric`, `MockK`, and other testing libraries to `app` and `feature/node` modules.
    -   Enabled Android resources in unit tests for the `feature/node` module.

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

This commit refactors `MeshConnectionManagerTest` to enhance its stability and correctness by addressing issues with coroutine testing and protobuf object creation.

- **Coroutine Testing:** Switched from `StandardTestDispatcher` and `TestScope` to `UnconfinedTestDispatcher` and `runTest(dispatcher)`. This change improves the reliability of asynchronous test execution and simplifies test structure.
- **Protobuf Initialization:** Updated the creation of `LocalConfig` and `Config` objects to use the standard builder pattern (`LocalConfig.newBuilder()`) instead of the deprecated `localConfig {}` DSL.
- **Resource Mocking:** Added mocking for `StringResources` to prevent `MissingResourceException` during test runs, ensuring that UI-related string lookups do not cause test failures.
- **Assertions:** Replaced simple `assert()` calls with JUnit's `assertEquals()` for more descriptive failure messages.
- **Test Logic:** Enhanced the `Disconnected state stops services` test to ensure it transitions through a `Connected` state first, guaranteeing the `Disconnected` state change has a meaningful effect to verify.

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