fix(exec): remove ad-hoc shell comment stripping from _guard_command

- Removes match_text regex that stripped # comments before pattern matching
(broke on quoted # inside strings)
- allow_patterns now run re.fullmatch against the full lowercased command
- deny_patterns search the original lowercased command
- Replaces comment-stripping test with comment-tail bypass regression
(touch canary # echo allowlisted must be blocked)
- Adds Re-bin regression for quoted hash + blocked command
(echo "#" followed by blocked command must be caught)
- All 10 tests pass

Signed-off-by: axelray-dev <110029405+axelray-dev@users.noreply.github.com>

nanobot/agent/tools/shell.py

@@ -598,17 +598,16 @@ class ExecTool(Tool):
         """Best-effort safety guard for potentially destructive commands."""
         cmd = command.strip()
         lower = cmd.lower()
-        match_text = re.sub(r"(^|[^\\])#.*$", r"\1", lower).strip()
 
         # allow_patterns take priority over deny_patterns so that users can
         # exempt specific commands (e.g. "rm -rf" inside a build directory)
         # from the hardcoded deny list via configuration.
         explicitly_allowed = bool(self.allow_patterns) and any(
-            re.fullmatch(p, match_text) for p in self.allow_patterns
+            re.fullmatch(p, lower) for p in self.allow_patterns
         )
         if not explicitly_allowed:
             for pattern in self.deny_patterns:
-                if re.search(pattern, match_text):
+                if re.search(pattern, lower):
                     return "Error: Command blocked by deny pattern filter"
 
             if self.allow_patterns: