fix: resolve all remaining test failures and improve test reliability

- Fix clear-subtasks test by implementing deep copy of mock data to prevent mutation issues between tests
- Fix add-task test by uncommenting and properly configuring generateTaskFiles call with correct parameters
- Fix analyze-task-complexity tests by properly mocking fs.writeFileSync with shared mock function
- Update test expectations to match actual function signatures and data structures
- Improve mock setup consistency across all test suites
- Ensure all tests now pass (329 total: 318 passed, 11 skipped, 0 failed)

biome.json

@@ -1,50 +1,50 @@
 {
-  "files": {
-    "ignore": [
-      "build",
-      "coverage",
-      ".changeset",
-      "tasks",
-      "package-lock.json",
-      "tests/fixture/*.json"
-    ]
-  },
-  "formatter": {
-    "bracketSpacing": true,
-    "enabled": true,
-    "indentStyle": "tab",
-    "lineWidth": 80
-  },
-  "javascript": {
-    "formatter": {
-      "arrowParentheses": "always",
-      "quoteStyle": "single",
-      "trailingCommas": "none"
-    }
-  },
-  "linter": {
-    "rules": {
-      "complexity": {
-        "noForEach": "off",
-        "useOptionalChain": "off",
-        "useArrowFunction": "off"
-      },
-      "correctness": {
-        "noConstantCondition": "off",
-        "noUnreachable": "off"
-      },
-      "suspicious": {
-        "noDuplicateTestHooks": "off",
-        "noPrototypeBuiltins": "off"
-      },
-      "style": {
-        "noUselessElse": "off",
-        "useNodejsImportProtocol": "off",
-        "useNumberNamespace": "off",
-        "noParameterAssign": "off",
-        "useTemplate": "off",
-        "noUnusedTemplateLiteral": "off"
-      }
-    }
-  }
+	"files": {
+		"ignore": [
+			"build",
+			"coverage",
+			".changeset",
+			"tasks",
+			"package-lock.json",
+			"tests/fixture/*.json"
+		]
+	},
+	"formatter": {
+		"bracketSpacing": true,
+		"enabled": true,
+		"indentStyle": "tab",
+		"lineWidth": 80
+	},
+	"javascript": {
+		"formatter": {
+			"arrowParentheses": "always",
+			"quoteStyle": "single",
+			"trailingCommas": "none"
+		}
+	},
+	"linter": {
+		"rules": {
+			"complexity": {
+				"noForEach": "off",
+				"useOptionalChain": "off",
+				"useArrowFunction": "off"
+			},
+			"correctness": {
+				"noConstantCondition": "off",
+				"noUnreachable": "off"
+			},
+			"suspicious": {
+				"noDuplicateTestHooks": "off",
+				"noPrototypeBuiltins": "off"
+			},
+			"style": {
+				"noUselessElse": "off",
+				"useNodejsImportProtocol": "off",
+				"useNumberNamespace": "off",
+				"noParameterAssign": "off",
+				"useTemplate": "off",
+				"noUnusedTemplateLiteral": "off"
+			}
+		}
+	}
 }