feat(lang): add Qt QML language support

Vendor the MIT-licensed tree-sitter-qmljs grammar (a TypeScript superset with
declarative ui_* nodes) and wire .qml files through the full pipeline: language
enum, extension + display-name mapping, grammar shim, and a language spec that
reuses the JS/TS function/call/branch arrays and adds QML class/field/import
types (ui_inline_component, ui_property, ui_signal, ui_import).

QML files now produce Function nodes (incl. JS functions inside QML objects),
class/interface/enum nodes, imports and CALLS edges, so call chains through a
Qt project's .qml files can be traced. LICENSE vendored alongside the grammar.

Closes #42