style: apply safe ruff auto-fixes and exempt startup late imports

Run `ruff check app tests scripts --fix` with the configured rule set
(E4/E7/E9/F/I): import sorting (I001), f-strings without placeholders
(F541), lambda/variable/unused-import cleanups that ruff marks safe.
Nine files whose only ruff debt sits next to pre-existing pylint
import-resolution errors (lazy exports, sys.path script imports) or
whose "unused" imports are reached through attribute access by tests are
left untouched so the changed-file pylint gate and the benchmark tests
stay green; their diagnostics remain in the baseline.

app/startup/lifecycle/__init__.py and app/main.py import business
modules after cache composition, import-path and stdio setup on purpose
(the source comments document the contract), so declare E402
per-file-ignores for them instead of adding per-line noqa.

Ruff ratchet watermark drops from 498 to 100; sync the baseline fixture
and the optimization checklist figure.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

scripts/schema/exports.py

@@ -6,7 +6,6 @@ import importlib
 import sys
 from pathlib import Path
 
-
 PROJECT_ROOT = Path(__file__).resolve().parents[2]
 if str(PROJECT_ROOT) not in sys.path:
     sys.path.insert(0, str(PROJECT_ROOT))