Refactor architecture documentation and enhance security features

- Updated architecture constraints documentation to include detailed sections on technical, organizational, regulatory, environmental, and performance constraints.
- Created separate markdown files for each type of constraint for better organization and clarity.
- Revised the architecture scope section to provide a clearer overview of the system's key areas.
- Enhanced the solution strategy documentation with detailed explanations of the client-server architecture, technology choices, trade-offs, and future considerations.
- Added comprehensive descriptions of backend and frontend components, middleware, and utilities in the architecture documentation.
- Migrated UI, templates, and styling notes to a dedicated section for better structure.
- Updated requirements.txt to include missing dependencies.
- Refactored user authentication logic in the users.py and security.py files to improve code organization and maintainability, including the integration of OAuth2 password bearer token handling.

docs/architecture/05_blocks/05_01_architecture_overview.md

@@ -0,0 +1,13 @@
+---
+title: '05 — Architecture Overview'
+description: "This overview complements architecture with a high-level map of CalMiner's module layout and request flow."
+status: draft
+---
+
+This overview complements [architecture](README.md) with a high-level map of CalMiner's module layout and request flow.
+
+Refer to the detailed architecture chapters in `docs/architecture/`:
+
+- Module map & components: [Building Block View](../05_building_block_view.md)
+- Request flow & runtime interactions: [Runtime View](../06_runtime_view.md)
+- Simulation roadmap & strategy: [Solution Strategy](../04_solution_strategy.md)