chore: add Flake8 linting config with baseline ignore rules

Adds .flake8 config and registers the flake8 pre-commit hook scoped to
python/ at rev 7.3.0. Baseline ignore rules (E501, F401, F541, F841,
E722, E402, E741, F811, F821, F824, E231) suppress existing violations
so the hook passes cleanly on the current codebase.

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

.flake8

@@ -0,0 +1,24 @@
+[flake8]
+max-line-length = 100
+extend-ignore =
+    E203,
+    W503,
+    E501,
+    F401,
+    F541,
+    F841,
+    F811,
+    F821,
+    F824,
+    E722,
+    E402,
+    E741,
+    E231
+exclude =
+    .git,
+    __pycache__,
+    dist,
+    build,
+    .eggs,
+    .venv,
+    node_modules