feat(sensor): Added sensor hal modules

[RoshanMGanesh]

Summary

Implements the full Sensor HAL module for Sprint 2. Adds sensor_hal.c and sensor_hal.h with ADC reads for battery temperature (LM35, CH0), motor temperature (LM35, CH1), battery current (ACS712-20A, CH2), battery voltage (resistor divider, CH3), and throttle position (potentiometer, CH4).

Type of Change

• 🆕 New feature / user story
• 🐛 Bug fix
• ♻️ Refactor (no behaviour change)
• 📝 Documentation only
• 🔧 CI/CD or tooling change
• 🔒 Security fix

Related Issue

Closes #23 #22 #24 #25 #26 #27 #28

Changes Made

• Added core/src/sensor_hal.c - full implementation of all 8 sensor read functions plus sensor_init(), sensor_read_all(), sensor_enable_i2c_temp() (stub), and sensor_get_temp_backend()
• Added core/inc/sensor_hal.h - public interface with Doxygen comments for every function, including Sprint 5 I2C preparation stubs
• Updated drivers/STM32_HAL/stm32_stubs.c - added stub implementations for all HAL GPIO, ADC, and timer functions used by the sensor module
• Added tests/test_sensor_hal.c - 22 unit tests covering all sensor read functions, boundary conditions, null pointer guards, ADC channel isolation, and GPIO debounce logic
• Added tests/mocks/mock_stm32_hal_adc.c/.h - full mock with per-channel value injection, start error, and poll timeout injection
• Added tests/mocks/mock_stm32_hal_gpio.c/.h - full mock with per-pin state control and mock_hal_set_tick() for debounce testing
• Added tests/mocks/mock_stm32_hal_tim.c/.h - mock with encoder count injection, ARR/CCR1 access, and PWM start error injection

How to Test This PR

1. Clone the branch: git checkout feat/sensor-hal
2. Build the test suite: cd tests && mkdir -p build && cd build && cmake .. -DCMAKE_BUILD_TYPE=Debug && make

Testing Done by Author

• Unit tests written for new/changed code
• All existing tests pass locally (cd Tests/build && ./test_runner → 0 Failures)
• Cppcheck passes locally (cppcheck --error-exitcode=1 -I core/Inc core/src/)
• Code compiled successfully (cmake --build build)
• Tested in Wokwi simulation (if applicable)
• UART output verified (if applicable)
• No new compiler warnings (-Wall -Wextra clean)

Code Quality Checklist

• Code follows naming conventions from 06_CODING_STANDARDS.md
• All public functions have Doxygen-style comments (@brief, @param, @retval)
• No magic numbers — all constants are in ev_config.h
• All function parameters are validated (null checks where applicable)
• Return values of all called functions are checked
• All switch statements have a default case
• All if/for/while blocks use { braces even for single lines

Documentation

• README.md updated if new setup steps are needed
• Inline /* TODO: */ comments added for any deferred work

---

Reviewer checklist:

• Code logic is correct and matches the linked issue requirements
• Tests are meaningful (not just "assert(1 == 1)")
• No obvious security or safety issues
• Comments are clear and accurate