refactor: fix unused imports, long lines, and type issues

Remove 35+ unused imports across 20+ files (W0611). Wrap 19 lines
to fit under 100 character limit (C0301). Add type casts and
annotations in egress_addon_core.py to resolve pyright errors
caused by JSON parsing of untyped objects.

Key changes:
- Remove unused imports (abstractmethod, mock utilities, etc)
- Split long lines at logical breaks (method calls, error messages)
- Add typing.cast() for proper type inference in JSON parsing
- Explicit type annotations for dict/list accesses

Results:
- Pylint rating: 8.73/10
- egress_addon_core.py: 0 pyright errors (was 15)
- All W0611 and C0301 issues fixed

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

bot_bottle/backend/smolmachines/local_registry.py

@@ -61,7 +61,10 @@ REGISTRY_IMAGE = os.environ.get(
 # narrow.
 CRANE_IMAGE = os.environ.get(
     "BOT_BOTTLE_CRANE_IMAGE",
-    "gcr.io/go-containerregistry/crane@sha256:0ae17ecb34315aa7cbff28f6eddee3b7adae0b2f90101260d990804db1eb0084",
+    (
+        "gcr.io/go-containerregistry/crane@sha256:"
+        "0ae17ecb34315aa7cbff28f6eddee3b7adae0b2f90101260d990804db1eb0084"
+    ),
 )