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>

src/Navigation/Bottom.tsx

@@ -1,7 +1,6 @@
 import React, { useEffect } from 'react';
 import {
     View,
-    Text,
     TouchableOpacity,
     StyleSheet,
     Dimensions,
@@ -24,10 +23,6 @@ import { useTheme } from '../Hooks/useTheme';
 import { typography } from '../theme/typography';
 // import EditableExcel from '../Screens/Tender/Component/EnvelopeCExcelPreview';
 
-const { width } = Dimensions.get('window');
-const TAB_BAR_HEIGHT = 70; // Slightly taller for premium feel
-const TAB_BUTTON_WIDTH = width / 4;
-
 const Tab = createBottomTabNavigator();
 
 const TabButton = ({ route, isFocused, onPress }: any) => {
@@ -55,9 +50,11 @@ const TabButton = ({ route, isFocused, onPress }: any) => {
             scale.value = withTiming(0, { duration: 200 });
             translateY.value = withSpring(0, { damping: 12, stiffness: 100 });
         }
+    // Intentionally runs only when isFocused changes; other deps are stable or recreated each render.
+    // eslint-disable-next-line react-hooks/exhaustive-deps
     }, [isFocused]);
 
-    const animatedPillStyle = useAnimatedStyle(() => {
+    useAnimatedStyle(() => {
         return {
             transform: [{ scale: scale.value }],
             opacity: interpolate(scale.value, [0, 1], [0, 1], Extrapolation.CLAMP),
@@ -86,6 +83,9 @@ const TabButton = ({ route, isFocused, onPress }: any) => {
             onPress={onPress}
             style={styles.tabButton}
             activeOpacity={0.8}
+            accessibilityRole="tab"
+            accessibilityState={{ selected: isFocused }}
+            accessibilityLabel={`${route.name} tab`}
         >
             <View style={styles.tabContent}>
                 <Animated.View style={animatedIconStyle}>
@@ -119,8 +119,8 @@ const TabButton = ({ route, isFocused, onPress }: any) => {
     );
 };
 
-const CustomTabBar = ({ state, descriptors, navigation }: any) => {
-    const { colors, shadows } = useTheme();
+const CustomTabBar = ({ state, navigation }: any) => {
+    const { colors } = useTheme();
     const { width: windowWidth } = Dimensions.get('window');
     const TAB_BAR_WIDTH = windowWidth - 40; // 20 margin each side
     const TAB_PADDING_H = 10; // 5 padding left + 5 padding right
@@ -134,6 +134,8 @@ const CustomTabBar = ({ state, descriptors, navigation }: any) => {
             stiffness: 150,
             mass: 0.5,
         });
+    // Intentionally runs only when the selected tab index changes; other deps are stable or recreated each render.
+    // eslint-disable-next-line react-hooks/exhaustive-deps
     }, [state.index]);
 
     const animatedIndicatorStyle = useAnimatedStyle(() => {