✨🧪⬆➕ workspace, varo: Implement RNG with ChaCha8 and add optimization function

- Updated `Cargo.toml` and `Cargo.lock` to downgrade `rand_core` to 0.6.4 and add `rand_chacha` dependency with `serde1` feature.
- Implemented `Rng` struct wrapping `ChaCha8Rng` with seed initialization, stream selection, and number generation methods.
- Added `rng_new`, `rng_from_seed`, `rng_set_stream`, `rng_next_u32`, `rng_next_u64`, `rng_fill_bytes`, `rng_gen_f32`, and `rng_gen_gaussian` functions.
- Made `value` field in `Score` and `values` field in `OptimizationResult` public.
- Implemented `Distribution::sample` method that generates Gaussian numbers when moments are available.
- Added `From<f32>` implementation for `Score`.
- Implemented `optimize` function that evaluates candidates using cloned RNG streams and returns sorted results.
- Added integration test `test_optimize` that verifies optimization sorting behavior.

Cargo.lock

@@ -1373,7 +1373,7 @@ checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
 dependencies = [
  "libc",
  "rand_chacha",
- "rand_core 0.6.4",
+ "rand_core",
 ]
 
 [[package]]
@@ -1383,7 +1383,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
 dependencies = [
  "ppv-lite86",
- "rand_core 0.6.4",
+ "rand_core",
+ "serde",
 ]
 
 [[package]]
@@ -1395,12 +1396,6 @@ dependencies = [
  "getrandom 0.2.16",
 ]
 
-[[package]]
-name = "rand_core"
-version = "0.9.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "99d9a13982dcf210057a8a78572b2217b667c3beacbf3a0d8b454f6f82837d38"
-
 [[package]]
 name = "redox_syscall"
 version = "0.5.13"
@@ -1423,7 +1418,7 @@ dependencies = [
  "num-traits",
  "pkcs1",
  "pkcs8",
- "rand_core 0.6.4",
+ "rand_core",
  "signature",
  "spki",
  "subtle",
@@ -1554,7 +1549,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "77549399552de45a898a580c1b41d445bf730df867cc44e6c0233bbc4b8329de"
 dependencies = [
  "digest",
- "rand_core 0.6.4",
+ "rand_core",
 ]
 
 [[package]]
@@ -2083,7 +2078,8 @@ version = "0.1.0"
 dependencies = [
  "blake3",
  "digest",
- "rand_core 0.9.3",
+ "rand_chacha",
+ "rand_core",
  "serde",
  "serde_json",
  "tempfile",