fix(lint): restore noqa directives and register custom codes with ruff

Reverts the noqa: removal — the architecture validators (SVC-006,
SEC-034, MOD-004, API-007) use these to skip known-safe violations.
Added ruff lint.external config so ruff treats them as valid codes.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pyproject.toml

@@ -18,6 +18,7 @@ include = ["app*", "models*", "middleware*", "storage*"]
 line-length = 88
 target-version = "py311"
 
+
 # Exclude directories
 exclude = [
     ".git",
@@ -34,6 +35,9 @@ exclude = [
 ]
 
 [tool.ruff.lint]
+# Allow custom architecture validator codes in # noqa directives (e.g., SEC-034, SVC-006)
+external = ["SEC", "SVC", "MOD", "API", "ARCH", "PERF"]
+
 # Enable comprehensive rule sets
 select = [
     "E",     # pycodestyle errors