chore: rename Tiji→Kangkang test imports + scheme + sync docs

Rename @testable imports across all test/UI test files after the Tiji→Kangkang
project rename in 44ed01a. Add shared scheme. Sync CLAUDE.md / W2 plan / spec
v1.0 to current scope (Symptom feature noted, C1/C2 flow lockdown).

康康/App/KangkangApp.swift

@@ -2,7 +2,7 @@ import SwiftUI
 import SwiftData
 
 @main
-struct TijiApp: App {
+struct KangkangApp: App {
     var sharedModelContainer: ModelContainer = {
         let schema = Schema([
             Indicator.self,