feat(03-01): add error handling for action flow

- Add docker-error route to Check Match Count switch (matchCount < 0)
- Add Send Docker Error node for Docker connection failures
- Route Docker API errors to user-facing error messages
- Ensure all error paths reach a Send Message node (no silent failures)
- Error messages include diagnostic details per CONTEXT.md requirements

n8n-workflow.json

@@ -246,6 +246,29 @@
       "parameters": {
         "rules": {
           "values": [
+            {
+              "id": "docker-error",
+              "conditions": {
+                "options": {
+                  "caseSensitive": true,
+                  "leftValue": "",
+                  "typeValidation": "strict"
+                },
+                "conditions": [
+                  {
+                    "id": "count-negative",
+                    "leftValue": "={{ $json.matchCount }}",
+                    "rightValue": "0",
+                    "operator": {
+                      "type": "number",
+                      "operation": "lt"
+                    }
+                  }
+                ],
+                "combinator": "and"
+              },
+              "renameOutput": false
+            },
             {
               "id": "no-match",
               "conditions": {
@@ -443,6 +466,28 @@
           "name": "Telegram API"
         }
       }
+    },
+    {
+      "parameters": {
+        "resource": "message",
+        "operation": "sendMessage",
+        "chatId": "={{ $json.chatId }}",
+        "text": "={{ $json.text }}",
+        "additionalFields": {
+          "parse_mode": "HTML"
+        }
+      },
+      "id": "telegram-send-docker-error",
+      "name": "Send Docker Error",
+      "type": "n8n-nodes-base.telegram",
+      "typeVersion": 1.2,
+      "position": [1780, 200],
+      "credentials": {
+        "telegramApi": {
+          "id": "telegram-credential",
+          "name": "Telegram API"
+        }
+      }
     }
   ],
   "connections": {
@@ -574,6 +619,13 @@
     },
     "Check Match Count": {
       "main": [
+        [
+          {
+            "node": "Send Docker Error",
+            "type": "main",
+            "index": 0
+          }
+        ],
         [
           {
             "node": "Format No Match",