refactor(backend): clean up models setup, improve ip utils, add adr docs

- Extract ADR documents for architectural decisions (SQLite, FastAPI, React, APScheduler, Scheduler)
- Refactor setup.py: improve code structure and readability
- Add IP validation utilities with test coverage
- Update frontend components (BanTable, HistoryPage)
- Add pre-commit hooks and CONTRIBUTING.md
- Add .editorconfig for consistent coding standards

.editorconfig

@@ -0,0 +1,33 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+
+[*.py]
+indent_style = space
+indent_size = 4
+
+[*.{js,ts,tsx,jsx}]
+indent_style = space
+indent_size = 2
+
+[*.md]
+indent_style = space
+indent_size = 2
+
+[Dockerfile]
+indent_style = space
+indent_size = 4
+
+[*.yml]
+indent_style = space
+indent_size = 2
+
+[*.yaml]
+indent_style = space
+indent_size = 2
+
+[Makefile]
+indent_style = tab