feat(p10-1c-jk): tree-sitter-java AST extractor (JavaAstExtractor)

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

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

@@ -0,0 +1,36 @@
+// sample.java
+package com.kebab.chunk;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+/**
+ * Heading-aware Markdown chunker.
+ */
+public class MdHeadingV1Chunker {
+    private final String name;
+
+    public MdHeadingV1Chunker(String name) {
+        this.name = name;
+    }
+
+    public List<String> chunkDoc(String input) {
+        return List.of(name, input);
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public static class Builder {
+        private String name;
+        public Builder withName(String n) { this.name = n; return this; }
+        public MdHeadingV1Chunker build() { return new MdHeadingV1Chunker(name); }
+    }
+}
+
+interface Stringer {
+    String asString();
+}
+
+enum Mode { DEFAULT, FAST }