feat(p10-1a-2): tree-sitter-rust AST extractor (parser-side)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/kebab-parse-code/tests/fixtures/sample.rs

@@ -0,0 +1,35 @@
+//! sample fixture
+
+use std::fmt;
+
+const ANSWER: u32 = 42;
+
+/// Doc comment on a free fn.
+pub fn parse(input: &str) -> usize {
+    input.len()
+}
+
+pub struct Foo {
+    pub n: u32,
+}
+
+impl Foo {
+    /// method doc
+    pub fn double(&self) -> u32 {
+        self.n * 2
+    }
+
+    fn name() -> &'static str {
+        "foo"
+    }
+}
+
+pub trait Greet {
+    fn hello(&self) -> String;
+}
+
+mod inner {
+    pub fn helper() -> bool {
+        true
+    }
+}