chore(serve): clarify path handling logic and add comments

- Added detailed comments to `serve.rs` to explain URI path resolution, error cases, and file streaming.
- Improved readability of path slicing and fallback logic.
- Updated dependencies in `Cargo.toml` and `Cargo.lock` as needed.

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Cargo.toml

@@ -32,6 +32,7 @@ tracing-subscriber = { version = "0.3.19", features = ["env-filter"] }
 clap = { version = "4.5.34", features = ["derive"] }
 serde_repr = "0.1.20"
 serde_json = "1.0.140"
+mime_guess = "2.0.5"
 
 [profile.dev]
 incremental = true          # Compile your binary in smaller steps.