Add cmdforge remove command for project dependencies

- `cmdforge remove <tool>` removes a dependency from cmdforge.yaml
- Matches by exact name or short name (e.g., both "eli5" and "official/eli5" work)
- Returns exit code 1 if dependency not found
- Complements `cmdforge add` for full manifest management

Co-Authored-By: Claude Opus 4.5 <[email protected]>

src/cmdforge/manifest.py

@@ -141,6 +141,31 @@ class Manifest:
 
         self.dependencies.append(Dependency(name=name, version=version))
 
+    def remove_dependency(self, name: str) -> bool:
+        """Remove a dependency by name.
+
+        Args:
+            name: Tool name (can be qualified like 'official/tool' or just 'tool')
+
+        Returns:
+            True if dependency was removed, False if not found
+        """
+        # Try exact match first
+        for i, dep in enumerate(self.dependencies):
+            if dep.name == name:
+                self.dependencies.pop(i)
+                return True
+
+        # Try matching just the tool name part (without owner)
+        short_name = name.split("/")[-1] if "/" in name else name
+        for i, dep in enumerate(self.dependencies):
+            dep_short = dep.name.split("/")[-1] if "/" in dep.name else dep.name
+            if dep_short == short_name:
+                self.dependencies.pop(i)
+                return True
+
+        return False
+
 
 def find_manifest(start_dir: Optional[Path] = None) -> Optional[Path]:
     """