feat(learning-harness): TypeScript and TSX rows parse under the semantic extra

Task 1.4. The optional extra gains the TypeScript grammar wheel, which ships two
grammars: a file with JSX needs the JSX-aware one and plain TypeScript needs the
other, so the parser picks by file suffix while the parsed file keeps the
language it was given. The walker already treated TypeScript as JavaScript, so
nothing else changes.

Eighteen agent-vfc rows and every TypeScript absence row were counted as
unsupported before this and could not be scored at all. They now parse on both
sides. The core install stays zero-dependency and the extra-free suite still
skips these tests.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01T7XD7x5KonMdmGRkp63EQG

pyproject.toml

@@ -26,6 +26,7 @@ semantic = [
     "tree-sitter>=0.23,<0.27",
     "tree-sitter-python>=0.23",
     "tree-sitter-javascript>=0.23",
+    "tree-sitter-typescript>=0.23",
     "tree-sitter-c>=0.23",
     "tree-sitter-cpp>=0.23",
     "tree-sitter-java>=0.23",