Pin dependencies to exact versions in requirements.txt for reproducible builds

What is the issue?

requirements.txt lists dependencies without pinned versions, meaning pip installs the latest compatible versions each time. This makes the environment non-deterministic: different developers and CI runs can end up with different package versions, leading to inconsistent behavior or unexpected breakages.

(Suggested by @Pa04rth in #854)

Expected Behaviour

Every pip install -r requirements.txt should produce an identical environment regardless of when it is run.

Actual Behaviour

Dependencies are unpinned (e.g. Flask, click), so pip resolves to whatever is latest at install time.

Steps to reproduce

1. Open requirements.txt and note entries like Flask, click have no version pins.
2. Create a fresh virtual environment and run pip install -r requirements.txt.
3. Run pip freeze and observe that pip has resolved specific versions not specified in requirements.txt, showing the environment is determined at install time.

Start by opening requirements.txt and reviewing the unpinned entries such as Flask and click. Run pip install -r requirements.txt in a fresh virtual environment, then use pip freeze to inspect the resolved versions. Done means requirements.txt pins its dependencies so repeated installations resolve to the same specified versions.