feat: implement comprehensive configuration management system with multi-mirror support

- Add ServerSettings class with pydantic-settings for type-safe configuration
- Support multiple PyPI mirror sources with priority-based fallback mechanism
- Implement RepositoryConfig and RepositoryManager for multi-repository support
- Add environment variable support for all configuration options
- Include private repository authentication configuration
- Add advanced dependency analysis settings (max depth, concurrency, security)
- Provide secure credential management with sensitive data masking
- Update documentation and configuration examples
- Add comprehensive test suite with 23 test cases covering all features
- Include demo script showcasing multi-mirror configuration capabilities

Configuration features:
- Primary, additional, and fallback index URLs
- Automatic duplicate URL removal with priority preservation
- Runtime configuration reloading
- Integration with repository manager for seamless multi-source queries

Signed-off-by: longhao <hal.long@outlook.com>

nox_actions/codetest.py

@@ -12,11 +12,14 @@ def pytest(session: nox.Session) -> None:
     session.install(".")
     session.install("pytest", "pytest-cov", "pytest-mock", "pytest-asyncio")
     test_root = os.path.join(THIS_ROOT, "tests")
-    session.run("pytest", f"--cov={PACKAGE_NAME}",
-                "--cov-report=xml:coverage.xml",
-                "--cov-report=term-missing",
-                f"--rootdir={test_root}",
-                env={"PYTHONPATH": THIS_ROOT.as_posix()})
+    session.run(
+        "pytest",
+        f"--cov={PACKAGE_NAME}",
+        "--cov-report=xml:coverage.xml",
+        "--cov-report=term-missing",
+        f"--rootdir={test_root}",
+        env={"PYTHONPATH": THIS_ROOT.as_posix()},
+    )
 
 
 def mypy(session: nox.Session) -> None: