fix: remove dead delete+recreate and pin code, add poll fallback test

Phase 1 cleanup:
- Remove deletePost() method (dead code, replaced by PUT in-place updates)
- Remove _postInfo Map tracking (no longer needed)
- Remove pin/unpin API calls from watcher-manager.js (incompatible with PUT updates)
- Add JSDoc note on (edited) label limitation in _flushUpdate()
- Add integration test: test/integration/poll-fallback.test.js
- Fix addSession() lastOffset===0 falsy bug (0 was treated as 'no offset')
- Fix pre-existing test failures: add lastOffset:0 where tests expect backlog reads
- Fix pre-existing session-monitor test: create stub transcript files
- Fix pre-existing status-formatter test: update indent check for blockquote format
- Format plugin/ files with Prettier (pre-existing formatting drift)

plugin/plugin.json

@@ -0,0 +1,44 @@
+{
+  "id": "com.openclaw.livestatus",
+  "name": "OpenClaw Live Status",
+  "description": "Real-time agent status streaming with custom post type rendering and WebSocket updates.",
+  "homepage_url": "https://git.eeqj.de/ROOH/MATTERMOST_OPENCLAW_LIVESTATUS",
+  "support_url": "https://git.eeqj.de/ROOH/MATTERMOST_OPENCLAW_LIVESTATUS/issues",
+  "icon_path": "assets/icon.svg",
+  "min_server_version": "7.0.0",
+  "server": {
+    "executables": {
+      "linux-amd64": "server/dist/plugin-linux-amd64"
+    }
+  },
+  "webapp": {
+    "bundle_path": "webapp/dist/main.js"
+  },
+  "settings_schema": {
+    "header": "Configure the OpenClaw Live Status plugin.",
+    "footer": "",
+    "settings": [
+      {
+        "key": "SharedSecret",
+        "display_name": "Shared Secret",
+        "type": "text",
+        "help_text": "Shared secret for authenticating the watcher daemon. Must match the daemon's PLUGIN_SECRET env var.",
+        "default": ""
+      },
+      {
+        "key": "MaxActiveSessions",
+        "display_name": "Max Active Sessions",
+        "type": "number",
+        "help_text": "Maximum number of simultaneously tracked agent sessions.",
+        "default": 20
+      },
+      {
+        "key": "MaxStatusLines",
+        "display_name": "Max Status Lines",
+        "type": "number",
+        "help_text": "Maximum number of status lines to display per session.",
+        "default": 30
+      }
+    ]
+  }
+}