feat: Make mcp support an optional feature, disabled by default

Co-authored-by: aider (openai/andrew/openrouter/sonoma-sky-alpha) <aider@aider.chat>

Cargo.toml

@@ -42,7 +42,7 @@ comfy-table = "7.2.0"
 pwhash = "1.0.0"
 regex = "1.9.5"
 ringbuf = "0.3"
-rmcp = { version = "0.2.0", features = ["server"] }
+rmcp = { version = "0.2.0", features = ["server"], optional = true }
 rusqlite = { version = "0.37.0", features = ["bundled", "array", "chrono"] }
 rusqlite_migration = "2.3.0"
 serde = { version = "1.0.219", features = ["derive"] }
@@ -85,6 +85,9 @@ all-filter-plugins = []
 # Individual plugin features
 magic = ["magic"]
 
+# MCP feature (Model Context Protocol support)
+mcp = ["rmcp"]
+
 [dev-dependencies]
 tempfile = "3.3.0"
 rand = "0.8.5"