feat(djinit/templates/project): improve secret key formatting and generate requirements via uv

Remove leading space in SECRET_KEY assignment and replace uv pip compile with uv run python ... to produce requirements.txt.

New Features
- Introduce uv-driven dependency compilation in justfile.j2
- Ensure generated requirements.txt reflects project dependencies from pyproject.toml

Enhancements
- Align secret key configuration to match production standards (no extra whitespace)

Bug Fixes
- Eliminate accidental whitespace that could cause secret key validation issues

djinit/templates/project/env_sample.j2

@@ -1,6 +1,6 @@
 # Django settings
 DJANGO_SETTINGS_MODULE={{ project_name }}.settings.development
-SECRET_KEY= your-secret-key
+SECRET_KEY=your-secret-key
 ALLOWED_HOSTS=api.your-domain.com,www.your-domain.com
 
 {% if use_database_url %}

djinit/templates/project/justfile.j2

@@ -82,7 +82,7 @@ showmigrations:
 
 # Sync dependencies (uv equivalent of pip freeze)
 requirements:
-    uv pip compile
+    uv run python -c "import tomllib; p = tomllib.load(open('pyproject.toml', 'rb')); print('\n'.join(p['project']['dependencies']))" > requirements.txt
 
 # Run all linting and checks
 ci: