📝 Fix stale requirements.txt install command in the completion container guide

The migration to uv (#1472) deleted the root requirements.txt, but two references to it were left behind: the install step in docs/contributing.md and the build step in scripts/docker/Dockerfile.

Since scripts/docker/compose.yaml builds from that Dockerfile, \docker compose run typer bash\ currently fails at image build time with the file not found, so the documented workflow for testing shell completion cannot be followed at all.

The deleted requirements.txt started with \-e .\ plus the tests/docs requirement files. For this container only the project itself is needed, so \uv pip install -e .\ keeps the exact previous behaviour of installing Typer into the system Python, where ENV UV_SYSTEM_PYTHON=1 makes it land on PATH for \	yper --install-completion\.

Author: HyperionBurn

docs/contributing.md

@@ -37,7 +37,7 @@ root@79c4b9b70cbe:/code#
 Then inside the container, you can install `typer` with:
 
 ```console
-$ uv pip install -r requirements.txt
+$ uv pip install -e .
 ```
 
 Then, you can start the shell you want to use, the one where you want to try out completion:

scripts/docker/Dockerfile

@@ -25,4 +25,4 @@ COPY . /code
 
 WORKDIR /code
 
-RUN uv pip install -r requirements.txt
+RUN uv pip install -e .