fix: handle non-numeric manifest icon keys in get_extension_icon to prevent ValueError crash

[Copilot]

Fixes #131

Summary

get_extension_icon crashed with ValueError when a Chrome extension manifest's icons object contained non-numeric keys (e.g. "48x48", "icon") instead of pure integer strings like "48".

Root cause: max(manifest_icons.keys(), key=lambda x: int(x)) — int("48x48") raises ValueError.

Changes

• Filter manifest icon keys to numeric-only using k.isdigit() before calling max()
• Wrap the icon resolution block in if numeric_keys: so manifests with no numeric icon keys are skipped gracefully, falling through to the existing persisted-icon → placeholder fallback chain
• Simplified key=lambda x: int(x) → key=int

Review of PR #132

PR #132 (by @Th-Shivam) correctly identifies and targets the same bug. However, it has three issues this PR addresses:

Issue	PR #132	This PR
No numeric keys	Raises ValueError (caught by outer except Exception, logs misleading warning)	Skips gracefully with if numeric_keys:
isinstance(k, str) guard	Present (redundant — json.load always produces string keys)	Removed
Lambda verbosity	key=lambda x: int(x)	key=int

Testing

• CodeQL security scan: 0 alerts
• No existing tests broken
• Correct fallback behavior: extensions with non-numeric icon keys now silently fall through to the persisted icon or placeholder response