feat: sync content definitions from core repo

Copy all TOML content definitions from librefang core repo:
- 33 agent definitions (agents/*/agent.toml)
- 14 hand definitions with docs (hands/*/HAND.toml + SKILL.md)
- 25 integration templates (integrations/*.toml)
- 2 example skill definitions (skills/custom-skill-*)
- 1 new provider (providers/vertex-ai.toml)

Part of the framework-vs-content registry split (RFC v0.7).

integrations/elasticsearch.toml

@@ -0,0 +1,35 @@
+id = "elasticsearch"
+name = "Elasticsearch"
+description = "Search and manage Elasticsearch indices and documents through the MCP server"
+category = "data"
+icon = "🔍"
+tags = ["search", "database", "indexing", "analytics", "full-text"]
+
+[transport]
+type = "stdio"
+command = "npx"
+args = ["-y", "@elastic/mcp-server-elasticsearch"]
+
+[[required_env]]
+name = "ELASTICSEARCH_URL"
+label = "Elasticsearch URL"
+help = "The base URL of your Elasticsearch cluster (e.g., https://my-cluster.es.us-east-1.aws.found.io:9243)"
+is_secret = false
+get_url = ""
+
+[[required_env]]
+name = "ELASTICSEARCH_API_KEY"
+label = "Elasticsearch API Key"
+help = "An API key with read/write permissions for the target indices"
+is_secret = true
+get_url = ""
+
+[health_check]
+interval_secs = 60
+unhealthy_threshold = 3
+
+setup_instructions = """
+1. Obtain your Elasticsearch cluster URL from your Elastic Cloud dashboard or self-hosted instance configuration.
+2. Create an API key in Kibana (Stack Management > API Keys) with appropriate index permissions.
+3. Paste the cluster URL and API key into the fields above.
+"""