refactor(hal): graduate systimer hal driver into esp_hal_systimer

components/esp_hal_systimer/README.md

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+# ESP Hardware Abstraction Layer for System Timer Peripheral
+
+> [!NOTE]
+> This component is currently in beta. Its API, behavior, and compatibility may change at any time and without notice; backward compatibility is not guaranteed. Use caution when integrating into production systems.
+
+## Overview
+
+The ESP Hardware Abstraction Layer for System Timer Peripheral (`esp_hal_systimer`) provides a unified interface to interact with the system timer (SYSTIMER) peripheral across all ESP chip families. This component abstracts the hardware-specific details of different SYSTIMER implementations, enabling consistent usage patterns regardless of the underlying hardware.
+
+The SYSTIMER is a high-resolution timer used for:
+- System time tracking
+- FreeRTOS tick generation
+- High-precision timing operations
+- Event timer (ETM) trigger generation
+
+## Architecture
+
+The HAL architecture consists of two primary layers:
+
+1. **HAL Layer (Upper)**: Defines the operational sequences and data structures required to interact with the SYSTIMER peripheral, including:
+   - Initialization and de-initialization functions
+   - Counter value operations
+   - Alarm configuration and management
+   - Time conversion utilities
+   - Clock source configuration
+
+2. **Low-Level Layer (Bottom)**: Acts as a translation layer between the HAL and the register definitions in the `soc` component, handling:
+   - Register access abstractions
+   - Chip-specific register configurations
+   - Hardware feature compatibility
+   - Clock and prescaler settings
+
+## Features
+
+- Unified SYSTIMER interface across all ESP chip families
+- Support for multiple counters and alarms
+- High-resolution timing (typically 16MHz resolution)
+- Flexible clock source configuration
+- ETM (Event Timer Module) support where available
+- Platform-specific optimizations
+- IRAM-safe implementation for critical sections
+- ROM implementation support for certain chips
+- Chip-specific implementations contained in separate directories
+
+## Usage
+
+This component is primarily used by ESP-IDF system services such as:
+- **esp_timer**: High-resolution timer implementation
+- **FreeRTOS**: System tick generation
+- **esp_hw_support**: System time and clock management
+
+For advanced developers implementing custom timing solutions, the HAL functions can be used directly. However, please note that the interfaces provided by this component are internal to ESP-IDF and are subject to change.
+
+## Dependencies
+
+- `soc`: Provides chip-specific register definitions
+- `hal`: Core hardware abstraction utilities and macros
+- `esp_rom`: ROM function interfaces (when using ROM implementation)
+
+## ROM Implementation
+
+Some chips support using ROM-based SYSTIMER HAL implementations for reduced code size. This is controlled by the `CONFIG_HAL_SYSTIMER_USE_ROM_IMPL` configuration option. When enabled, the component uses ROM linker scripts to link against ROM functions instead of compiling the HAL implementation.