feat: add WhatsApp channel adapter (Phase 3c)

docs/plans/state.json

@@ -12,7 +12,7 @@
     },
     "p0-p1-implementation-plan": {
       "file": "2026-02-06-p0-p1-implementation-plan.md",
-      "status": "in_progress",
+      "status": "completed",
       "date": "2026-02-06",
       "summary": "7 features across 7 phases (0-6). Estimated 15-22 days total.",
       "phases": {
@@ -77,7 +77,7 @@
         },
         "phase_3_messaging_channels": {
           "priority": "P1",
-          "status": "in_progress",
+          "status": "completed",
           "description": "Discord, Slack, WhatsApp channel adapters",
           "sub_phases": {
             "3a_discord": {
@@ -113,7 +113,24 @@
               "test_status": "22/22 passing",
               "notes": "Socket Mode only (HTTP fallback deferred). Slash commands deferred. User ID used as senderName (display name resolution is a follow-up)."
             },
-            "3c_whatsapp": { "status": "not_started", "effort": "2-3 days" }
+            "3c_whatsapp": {
+              "status": "completed",
+              "effort": "2-3 days",
+              "files_created": [
+                "src/channels/whatsapp/adapter.ts",
+                "src/channels/whatsapp/adapter.test.ts",
+                "src/channels/whatsapp/index.ts"
+              ],
+              "files_modified": [
+                "src/config/schema.ts",
+                "src/channels/index.ts",
+                "src/daemon/index.ts",
+                "package.json"
+              ],
+              "new_dependencies": ["whatsapp-web.js"],
+              "test_status": "25/25 passing",
+              "notes": "QR code auth via LocalAuth. Session persistence via data_dir. Group messages filtered (DM only). Phone number allowlist. Headless Chrome with Puppeteer."
+            }
           },
           "planned_files": [
             "src/channels/discord/adapter.ts",
@@ -206,10 +223,10 @@
   },
 
   "overall_progress": {
-    "total_test_count": 494,
+    "total_test_count": 519,
     "all_tests_passing": true,
     "p0_completion": "3/3 (100%)",
-    "p1_completion": "3/4 (75%)",
-    "next_up": "phase_3c_whatsapp_adapter"
+    "p1_completion": "4/4 (100%)",
+    "next_up": "all_p0_p1_complete"
   }
 }