Improve derived generator ergonomics

RELEASE.md

@@ -0,0 +1,29 @@
+RELEASE_TYPE: minor
+
+This release makes several changes to `#[derive(DefaultGenerator)]` ([#149](https://github.com/hegeldev/hegel-rust/issues/149)):
+
+- Tuple variants now take field generators directly as positional arguments
+- Named variants use a closure that receives the default variant generator:
+- Generated method names are converted to snake_case instead of preserving PascalCase
+  - If this would produce a name collision, we keep the original casing for both method names.
+
+```rust
+enum Op {
+    Reset,
+    ReadWrite(usize, usize),
+    Configure { retries: u32, timeout: u64 },
+}
+
+// before
+let g = Op::default_generator();
+Op::default_generator()
+    .ReadWrite(g.default_ReadWrite().value_0(gs::just(42)).value_1(gs::just(43)))
+    .Configure(g.default_Configure().retries(gs::just(44)))
+
+// after
+Op::default_generator()
+    .read_write(gs::just(42), gs::just(43))
+    .configure(|g| g.retries(gs::just(44)))
+```
+
+Thanks to Rain for providing feedback on enum ergonomics!