Fix SSE stream discovery and add ESLint for WebUI

JavaScript fixes:
- Fix Invalid URL error in stream-discovery.js by adding window.location.origin as base URL
- Fix SSE race condition: ensure all stream_found events sent before complete event
- Comment unused eventType variable in stream-discovery.js
- Comment unused FrigateGenerator import in config-panel.js
- Fix quote style (double to single quotes)

Go fixes:
- Add sync.WaitGroup for result collector to prevent premature SSE closure
- Add logging for stream_found events
- Fix ERR_INCOMPLETE_CHUNKED_ENCODING by waiting for all streams to be sent

ESLint setup:
- Add ESLint v8.57.1 with .eslintrc.cjs config for ES2022 modules
- Add npm scripts for lint and lint:fix
- Update .gitignore for node_modules and package-lock.json

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

webui/package.json

@@ -0,0 +1,18 @@
+{
+  "name": "webui",
+  "version": "1.0.0",
+  "type": "module",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1",
+    "lint": "eslint web/js/**/*.js",
+    "lint:fix": "eslint web/js/**/*.js --fix"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "devDependencies": {
+    "eslint": "^8.57.1"
+  }
+}