feat: release v1.0.3 with flattened JSON output structure

- breaking: remove apache and network subdivisions from JSON output
- feat: all log fields now merged into single-level JSON structure
- feat: custom MarshalJSON() implementation for flat output
- chore: update ClickHouse schema to use single fields JSON column
- docs: update CHANGELOG.md and README.md with v1.0.3 changes
- build: bump version to 1.0.3 in build.sh and RPM spec

Migration notes:
- Existing ClickHouse tables need schema migration to use fields JSON column
- Replace apache JSON and network JSON columns with fields JSON column

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

CHANGELOG.md

@@ -5,6 +5,21 @@ All notable changes to logcorrelator are documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [1.0.3] - 2026-02-28
+
+### Changed
+
+- **Breaking**: Flattened JSON output structure - removed `apache` and `network` subdivisions
+- All log fields are now merged into a single-level JSON structure for easier parsing
+- ClickHouse schema updated: replaced `apache JSON` and `network JSON` columns with single `fields JSON` column
+
+### Technical Details
+
+- Custom `MarshalJSON()` implementation flattens all fields at the root level
+- Backward compatibility: existing ClickHouse tables need schema migration to use `fields JSON` column
+
+---
+
 ## [1.0.2] - 2026-02-28
 
 ### Fixed