chore(ios): add WebTermTests unit-test bundle target (W3 coordination point)

project.yml gains a bundle.unit-test target hosted by the app, wired to all
5 local packages (TestSupport test-doubles included) so T-iOS-11..14 VM tests
run via xcodebuild test. Coverage gate still counts only the 4 packages (§9).

ios/App/WebTermTests/WebTermTestsPlaceholder.swift

@@ -0,0 +1,9 @@
+import Testing
+@testable import WebTerm
+
+// Orchestrator-added placeholder so the WebTermTests bundle compiles before
+// W3 lands real ViewModel tests (T-iOS-11…14 own their test files here).
+@Test("WebTermTests bundle 可加载且能 @testable import WebTerm")
+func testBundleLoads() {
+    #expect(Bool(true))
+}