feat(core): make chunk limit configurable via CHUNK_LIMIT environment variable

[micari]

Summary

Makes the hardcoded chunk limit of 450,000 configurable through the CHUNK_LIMIT environment variable, following the same pattern as other configuration options like EMBEDDING_BATCH_SIZE.

Motivation

The chunk limit was previously hardcoded at 450,000, which limited flexibility for different use cases. Users with larger codebases or different performance requirements can now configure this value to suit their needs.

Changes

• ✅ Read CHUNK_LIMIT from environment variable with default of 450000
• ✅ Add validation to ensure minimum value of 1
• ✅ Add logging to display configured chunk limit value
• ✅ Update docs/getting-started/environment-variables.md with new variable
• ✅ Add CHUNK_LIMIT to .env.example
• ✅ Update MCP help message with advanced configuration section

Usage Examples

Global configuration (~/.context/.env):
```bash
CHUNK_LIMIT=1000000
```

Process environment variable:
```bash
CHUNK_LIMIT=1000000 npx @zilliz/claude-context-mcp@latest
```

Default behavior (no configuration):

• Falls back to 450000 (maintains backward compatibility)

Testing

• Follows the same pattern as EMBEDDING_BATCH_SIZE
• Backward compatible (defaults to 450000)
• Input validation (minimum value of 1)
• Logging added for debugging

Checklist

• Follows conventional commit format
• Documentation updated
• No breaking changes
• Consistent with existing codebase patterns

🤖 Generated with Claude Code