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/02_constraints/02_02_organizational_constraints.md

@@ -0,0 +1,18 @@
+---
+title: '02 — Organizational Constraints'
+description: 'Organizational constraints that affect architecture decisions.'
+status: draft
+---
+
+# Organizational Constraints
+
+> e.g., team skillsets, development workflows, CI/CD pipelines.
+
+Restrictions arising from organizational factors include:
+
+1. **Team Expertise**: The development team’s familiarity with FastAPI, SQLAlchemy, and frontend technologies like Jinja2 and Chart.js influences the architecture choices to ensure maintainability and ease of development.
+2. **Development Processes**: The adoption of Agile methodologies and CI/CD pipelines (using Gitea Actions) shapes the architecture to support continuous integration, automated testing, and deployment practices.
+3. **Collaboration Tools**: The use of specific collaboration and version control tools (e.g., Gitea) affects how code is managed, reviewed, and integrated, impacting the overall architecture and development workflow.
+4. **Documentation Standards**: The requirement for comprehensive documentation (as seen in the `docs/` folder) necessitates an architecture that is well-structured and easy to understand for both current and future team members.
+5. **Knowledge Sharing**: The need for effective knowledge sharing and onboarding processes influences the architecture to ensure that it is accessible and understandable for new team members.
+6. **Resource Availability**: The availability of hardware, software, and human resources within the organization can impose constraints on the architecture, affecting decisions related to scalability, performance, and feature implementation.