Increment 0: add XCTest target, testing process & 10x value plan

- Add TopManagerTests unit-test target (hosted, @testable import)
- 14 baseline tests for formatters and model math (all green)
- scripts/test.sh build+test loop driver
- docs/TESTING.md (5-gate process), docs/VALUE_PLAN.md (10x rubric)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

project.yml

@@ -33,3 +33,34 @@ targets:
         ASSETCATALOG_COMPILER_APPICON_NAME: AppIcon
     info:
       path: TopManager/Info.plist
+
+  TopManagerTests:
+    type: bundle.unit-test
+    platform: macOS
+    sources:
+      - path: TopManagerTests
+        excludes:
+          - "**/.DS_Store"
+    dependencies:
+      - target: TopManager
+    settings:
+      base:
+        PRODUCT_BUNDLE_IDENTIFIER: com.topmanager.TopManagerTests
+        GENERATE_INFOPLIST_FILE: YES
+        TEST_HOST: "$(BUILT_PRODUCTS_DIR)/TopManager.app/Contents/MacOS/TopManager"
+        BUNDLE_LOADER: "$(TEST_HOST)"
+        CODE_SIGN_STYLE: Automatic
+
+schemes:
+  TopManager:
+    build:
+      targets:
+        TopManager: all
+        TopManagerTests: [test]
+    run:
+      config: Debug
+    test:
+      config: Debug
+      targets:
+        - TopManagerTests
+      gatherCoverageData: false