feat: initial Silent Send browser extension

Chrome Manifest V3 extension that intercepts personal data and
substitutes it with user-defined replacements before sending to
Claude.ai. Hooks fetch() in the page's main world to catch API
requests, with bidirectional substitution (real→fake on send,
fake→real on display via reveal mode).

Includes popup UI with mapping management, live test/diff view,
activity log with badge count, options page with import/export,
and Shadow DOM traversal for Claude.ai compatibility.

https://claude.ai/code/session_01Dvgwe7XMoSxnWXkih8p1Cw

src/lib/storage.js

@@ -0,0 +1,113 @@
+/**
+ * Silent Send - Storage Manager
+ *
+ * Wraps chrome.storage.local with typed helpers for mappings,
+ * activity log, and settings.
+ */
+
+const KEYS = {
+  MAPPINGS: 'ss_mappings',
+  LOG: 'ss_activity_log',
+  SETTINGS: 'ss_settings',
+};
+
+const DEFAULT_SETTINGS = {
+  enabled: true,
+  showHighlights: false,
+  revealMode: false,
+  maxLogEntries: 200,
+  categories: ['name', 'email', 'phone', 'address', 'ssn', 'dob', 'general'],
+};
+
+const Storage = {
+  // --- Mappings ---
+
+  async getMappings() {
+    const result = await chrome.storage.local.get(KEYS.MAPPINGS);
+    return result[KEYS.MAPPINGS] || [];
+  },
+
+  async saveMappings(mappings) {
+    await chrome.storage.local.set({ [KEYS.MAPPINGS]: mappings });
+  },
+
+  async addMapping(mapping) {
+    const mappings = await this.getMappings();
+    const newMapping = {
+      id: crypto.randomUUID(),
+      real: mapping.real || '',
+      substitute: mapping.substitute || '',
+      category: mapping.category || 'general',
+      caseSensitive: mapping.caseSensitive ?? false,
+      enabled: mapping.enabled ?? true,
+      createdAt: Date.now(),
+    };
+    mappings.push(newMapping);
+    await this.saveMappings(mappings);
+    return newMapping;
+  },
+
+  async updateMapping(id, updates) {
+    const mappings = await this.getMappings();
+    const idx = mappings.findIndex((m) => m.id === id);
+    if (idx === -1) return null;
+    mappings[idx] = { ...mappings[idx], ...updates };
+    await this.saveMappings(mappings);
+    return mappings[idx];
+  },
+
+  async deleteMapping(id) {
+    const mappings = await this.getMappings();
+    const filtered = mappings.filter((m) => m.id !== id);
+    await this.saveMappings(filtered);
+  },
+
+  // --- Activity Log ---
+
+  async getLog() {
+    const result = await chrome.storage.local.get(KEYS.LOG);
+    return result[KEYS.LOG] || [];
+  },
+
+  async addLogEntry(entry) {
+    const settings = await this.getSettings();
+    const log = await this.getLog();
+
+    log.unshift({
+      ...entry,
+      id: crypto.randomUUID(),
+      timestamp: Date.now(),
+    });
+
+    // Trim to max entries
+    if (log.length > settings.maxLogEntries) {
+      log.length = settings.maxLogEntries;
+    }
+
+    await chrome.storage.local.set({ [KEYS.LOG]: log });
+  },
+
+  async clearLog() {
+    await chrome.storage.local.set({ [KEYS.LOG]: [] });
+  },
+
+  // --- Settings ---
+
+  async getSettings() {
+    const result = await chrome.storage.local.get(KEYS.SETTINGS);
+    return { ...DEFAULT_SETTINGS, ...(result[KEYS.SETTINGS] || {}) };
+  },
+
+  async saveSettings(settings) {
+    const current = await this.getSettings();
+    await chrome.storage.local.set({
+      [KEYS.SETTINGS]: { ...current, ...settings },
+    });
+  },
+};
+
+if (typeof globalThis !== 'undefined') {
+  globalThis.SilentSendStorage = Storage;
+}
+
+export default Storage;