5 error display and formatting

[lxsaah]

Closes #5

Added

• Error code system for embedded environments: Added numeric error codes (0x1000-0x7FFF) organized by category for fast error identification on embedded platforms. ([Error Display and Formatting #5])
• Platform-specific error formatting: Rich error messages with full context in std mode, compact format with error codes in no_std mode. ([Error Display and Formatting #5])
• Performance-optimized error handling: Added error_code() and error_category() const methods with <1μs lookup time and zero heap allocation on embedded targets. ([Error Display and Formatting #5])
• Comprehensive error categorization: Organized errors into 7 categories - Network (0x1000), Capacity (0x2000), Serialization (0x3000), Configuration (0x4000), Resource (0x5000), Hardware (0x6000), and Internal (0x7000). ([Error Display and Formatting #5])

Changed

• Enhanced error display formatting: Updated Display implementation for DbError to show "Error 0x{code}: {message}" format in no_std environments for better diagnostics. ([Error Display and Formatting #5])
• Expanded error documentation: Added detailed documentation covering error code ranges, platform-specific behavior, performance guarantees, and usage examples for embedded systems. ([Error Display and Formatting #5])

[Copilot]

Pull Request Overview

This PR implements a comprehensive error code system for AimDB's embedded environments, addressing issue #5. The implementation adds numeric error codes organized by category (0x1000-0x7FFF) to enable fast error identification on embedded platforms while maintaining rich error messages in std mode.

Key Changes

• Added numeric error codes (0x1000-0x7FFF) organized into 7 categories for embedded environments
• Enhanced error display formatting with platform-specific behavior (rich messages in std, compact codes in no_std)
• Implemented performance-optimized error_code() and error_category() const methods with <1μs lookup guarantees