🔧 Migrate from pip to uv for dependency management

[matrixise]

Description

Migrate the project's dependency management from pip to uv for faster and more reliable package installation and resolution.

Context

The project currently uses pip for installing dependencies, but already uses uv for compiling requirements files (as seen in requirements/*.txt headers). We should fully migrate to uv for all dependency management operations to benefit from its speed and improved dependency resolution.

Benefits

• Speed: uv is significantly faster than pip for package installation (10-100x in many cases)
• Better dependency resolution: More reliable conflict detection and resolution
• Consistency: Already using uv for requirements compilation, this would unify our tooling
• Lock file support: Better reproducibility across environments

Scope

• Update Docker configuration to use uv pip install instead of pip install
• Update local development documentation (CLAUDE.md) with uv installation instructions
• Update CI/CD pipelines if applicable
• Update Taskfile/Makefile commands to use uv
• Update development setup scripts
• Test in all environments (local, Docker, Heroku)

References

• uv documentation
• Current usage: Already using uv pip compile for requirements files

Notes

This is a tooling change that should not affect the actual dependencies or application behavior, only the installation process.