feat: add schema versioning table and improve migration logic ...

- Introduced 'internal_metadata' table to track database version.
- Updated migrate_025_to_030 to use 'internal_metadata' presence as a version indicator.
- Updated 03_database_specification.md with the new table.
- Recorded in journal 20260223-0019.

feat: add MIME type support to documents ...

- Added 'mime' column to 'documents' table in db.rs.
- Implemented automatic MIME detection in mcp.rs 'add_item_text' tool.
- Updated search and retrieval tools in mcp.rs to return 'mime' information.
- Refreshed 03_database_specification.md to reflect the new column.
- Recorded work in journal 20260223-0015.

docs: reformat bilingual documents into separate blocks ...

- Reorganized Issue-2 journal, Issue Management rules, and Development Guide.
- Separated Japanese and English descriptions into distinct blocks for better readability.
- Issue-2.md (local sync file) was also updated but is excluded from git track.

docs: renumber specifications to ensure continuous sequence ...

- Renamed 06_development_guide.md to 05_development_guide.md.
- Renamed 07_ui_design_spec.md to 06_ui_design_spec.md.
- Updated journal to reflect the changes.

docs: correct placement of development guide and update records ...

- Restored development_guide.md to docs/specification/.
- Updated journal to reflect the separation of specs and rules.

feat: normalize database schema for document-chunk separation (Issue-2) ...

- Added 'documents' table for metadata.
- Refactored 'items' table for chunk storage.
- Updated MCP tools (add_item_text, search_text, etc.) to support the new schema.
- Updated technical documentation.

Docs: Separate technical specifications from project operational workflows

Docs/Chore: Establish bilingual (Japanese/English) issue policy and update dev guide

Docs: Modernize all specification documents to align with LSA-based architecture and new directory structure

Docs/Chore: Implement manual issue closure reminder and update development guide rules

Fix: untrack docs/issues from git and add to gitignore

Feat: implement two-way issue sync tool with GitBucket

Refactor: reorganization of root and source directories and fix Error 1412