fix: shrink release binary to stay under 1 MiB limit

- Move serde_json to [dev-dependencies]: it is only used in a #[cfg(test)]
  block in graph/types.rs, so it must not be linked into the release binary
- Add lto = true: whole-program dead-code elimination across crate boundaries
- Add codegen-units = 1: single codegen unit enables better optimization
- Add strip = "symbols": removes symbol table from the release binary

Together these bring the binary well under the 1 MiB project goal.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: adityamukho

Cargo.toml

@@ -8,7 +8,6 @@ authors = ["Aditya Mukhopadhyay"]
 
 [dependencies]
 serde = { version = "1.0", features = ["derive"] }
-serde_json = "1.0"
 postcard = { version = "1.0", features = ["alloc"] }
 crc32fast = "1.4"
 anyhow = "1.0"
@@ -18,10 +17,14 @@ clap = { version = "4.5", features = ["derive"] }
 
 [dev-dependencies]
 tempfile = "3"
+serde_json = "1.0"
 
 [features]
 default = []
 wasm = []
 
 [profile.release]
 panic = "abort"
+lto = true
+codegen-units = 1
+strip = "symbols"