feat: architecture refactor — core layer, spreadsheet engine, envelope bidding, tests

- Add src/core/ (config, errors, events, http, observability, storage, query)
- Add src/Spreadsheet/ engine with native POI backend and Excel bridge
- Add Envelope C spreadsheet flow and tender bidding envelope modules
- Consolidate components into src/components/, remove legacy Component/ and Hooks/
- Add registration state/validation, auth session guard, profile edit modules
- Add unit tests across axios, redux, bidding, registration, encryption, core
- Add CI workflow, docs (architecture, audit, DSC API spec), keystore example
- Remove tracked keystore binary; ignore scripts.zip

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

android/app/src/main/java/com/procure/excel/ExcelPackage.kt

@@ -0,0 +1,22 @@
+package com.procure.excel
+
+import com.facebook.react.ReactPackage
+import com.facebook.react.bridge.NativeModule
+import com.facebook.react.bridge.ReactApplicationContext
+import com.facebook.react.uimanager.ViewManager
+
+/**
+ * Registers [ExcelModule] with React Native. Added manually in
+ * MainApplication.getPackages(). Works under both the old and new architecture
+ * (the JS ExcelBridge resolves it via TurboModuleRegistry first, then the
+ * legacy NativeModules registry).
+ */
+class ExcelPackage : ReactPackage {
+    override fun createNativeModules(reactContext: ReactApplicationContext): List<NativeModule> =
+        listOf(ExcelModule(reactContext))
+
+    override fun createViewManagers(reactContext: ReactApplicationContext): List<ViewManager<*, *>> =
+        emptyList()
+}
+
+