Merge PR #4: use html2md on web_fetch (fixes #3) (spqrz)

web_fetch was returning raw HTML, which is verbose and hard for
the agent to consume. Add html2md dependency and convert HTML to
Markdown before truncation. Much cleaner output for normal pages;
no downsides.

Co-Authored-By: spqrz <spqrz386@gmail.com>
Co-Authored-By: Proof of Concept <poc@bcachefs.org>

Cargo.toml

@@ -20,6 +20,7 @@ edition.workspace = true
 
 [dependencies]
 anyhow = "1"
+html2md = "0.2"
 crossterm = { version = "0.29", features = ["event-stream", "bracketed-paste", "osc52"] }
 clap = { version = "4", features = ["derive"] }
 figment = { version = "0.10", features = ["env"] }