refactor: modernize code quality tooling with Ruff

- Replace black, isort, and flake8 with Ruff (all-in-one linter and formatter)
- Add comprehensive pyproject.toml configuration
- Simplify Makefile code quality targets
- Configure exclusions for venv/.venv in pyproject.toml
- Auto-fix 1,359 linting issues across codebase

Benefits:
- Much faster builds (Ruff is written in Rust)
- Single tool replaces multiple tools
- More comprehensive rule set (UP, B, C4, SIM, PIE, RET, Q)
- All configuration centralized in pyproject.toml
- Better import sorting and formatting consistency

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/core/environment.py

@@ -31,18 +31,18 @@ def get_environment() -> EnvironmentType:
     env = os.getenv("ENV", "").lower()
     if env in ["development", "dev", "local"]:
         return "development"
-    elif env in ["staging", "stage"]:
+    if env in ["staging", "stage"]:
         return "staging"
-    elif env in ["production", "prod"]:
+    if env in ["production", "prod"]:
         return "production"
 
     # Priority 2: ENVIRONMENT variable
     env = os.getenv("ENVIRONMENT", "").lower()
     if env in ["development", "dev", "local"]:
         return "development"
-    elif env in ["staging", "stage"]:
+    if env in ["staging", "stage"]:
         return "staging"
-    elif env in ["production", "prod"]:
+    if env in ["production", "prod"]:
         return "production"
 
     # Priority 3: Auto-detect from common indicators