fix(mermaid): switch to crates.io and patch dagre_rust panic

Switch mermaid-rs-renderer from git dependency to crates.io 0.1.

Vendor and patch dagre_rust 0.0.5 to fix upstream panic in
remove_edge_label_proxies() where unwrap() is called on None
when processing edge label proxies without edge references.

This enables sequence diagrams and state diagrams that previously
crashed the build.

Cargo.toml

@@ -37,4 +37,8 @@ serde    = { version = "1", features = ["derive"] }
 toml     = "0.8"
 
 # Diagram rendering
-mermaid-rs-renderer = { git = "https://github.com/1jehuang/mermaid-rs-renderer", default-features = false }
+mermaid-rs-renderer = { version = "0.1", default-features = false }
+
+# Patch dagre_rust to fix unwrap on None bug
+[patch.crates-io]
+dagre_rust = { path = "patches/dagre_rust" }