fix: SEARXNG_URL no longer includes /search suffix (provider adds it), sync all files

plugin.yaml

@@ -0,0 +1,6 @@
+name: research-agent
+version: "1.0.0"
+description: Perplexity-style web research tools — deep multi-step research, quick search, and YouTube analysis. Uses SearXNG + LLM synthesis. Ships deep_research, perplexity_search, youtube_analyze as native tool calls.
+requires_env:
+  - SEARXNG_URL
+  - LLM_MODEL