chore: switch license to MIT and add rand/serde dependencies

- License the crate as MIT only.
- Fill in package description and `readme` field.
- Add rand 0.9 and rand_distr 0.5 (the `StdRng` and Normal sampler the
  spec mandates as the single Rng type).
- Add optional serde 1 gated behind a `serde` feature flag for later
  derives on core data types.

Cargo.toml

@@ -2,5 +2,15 @@
 name = "heuropt"
 version = "0.1.0"
 edition = "2024"
+description = "A practical Rust toolkit for heuristic single-, multi-, and many-objective optimization."
+license = "MIT"
+readme = "README.md"
+
+[features]
+default = []
+serde = ["dep:serde"]
 
 [dependencies]
+rand = "0.9"
+rand_distr = "0.5"
+serde = { version = "1", features = ["derive"], optional = true }