v0.4.0

## What's Changed
* feat: Optimize MCP and AGENTS.md instructions, add snippet_lines by @Pringled in https://github.com/MinishLab/semble/pull/198
* fix: correctly read cache metadata as UTF-8 by @Pililink in https://github.com/MinishLab/semble/pull/203
* chore: Bump version by @Pringled in https://github.com/MinishLab/semble/pull/205
* fix: Ensure savings are correct when max_snippet_lines is used by @Pringled in https://github.com/MinishLab/semble/pull/206

## New Contributors
* @Pililink made their first contribution in https://github.com/MinishLab/semble/pull/203

## Migration notes
- For CLI/sub-agent users: this release features optimizations to the Semble prompts and MCP instructions that further improve performance and reduce costs. We recommend running `semble install` after upgrading. The MCP instructions are automatically updated when installing the latest version.
- The CLI and MCP search result JSON format changed in this release. Results are now flattened, so all fields are returned directly on each result object instead of under a nested `chunk` object. The `language` and `location` fields are no longer included in CLI/MCP formatted output as they added tokens while they can just be inferred from existing fields.

**Full Changelog**: https://github.com/MinishLab/semble/compare/v0.3.4...v0.4.0