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>

tests/integration/test_capability_apply.py

@@ -24,7 +24,6 @@ this test runs in DinD too — no act_runner skip needed.
 from __future__ import annotations
 
 import os
-import shutil
 import subprocess
 import tempfile
 import time
@@ -32,7 +31,7 @@ import unittest
 from pathlib import Path
 
 from bot_bottle import supervise
-from bot_bottle.backend.docker import bottle_state, capability_apply
+from bot_bottle.backend.docker import bottle_state
 from bot_bottle.backend.docker.capability_apply import apply_capability_change
 from bot_bottle.backend.docker.network import (
     network_create_egress,

tests/integration/test_smolmachines_bundle_bringup.py

@@ -12,7 +12,6 @@ localhost-reach / egress-port-bypass probes) lives in chunk 2d."""
 
 from __future__ import annotations
 
-import json
 import os
 import subprocess
 import time