fix(extract): extract Spring routes from Kotlin controllers

[jsw6701]

Fixes #565.

What

Spring MVC routing annotations on Kotlin @RestController classes were not extracted as routes, while the same annotations on Java controllers worked.

Root cause: try_route_from_annotation resolved the annotation name via the name field (ts_node_child_by_field_name(annotation, "name")). tree-sitter-kotlin annotation nodes have no name field — the name lives in a nested type_identifier under user_type / constructor_invocation — so the lookup returned null and every Kotlin route was dropped (0 decorator-source routes). Arguments are likewise carried under constructor_invocation's value_arguments (each wrapped in value_argument), not Java's argument_list.

Change (internal/cbm/extract_defs.c)

• annotation_name_node() — falls back to the Kotlin nested-type_identifier shape when the name field is absent (Java path unchanged).
• annotation_args_node() — resolves Kotlin's value_arguments under constructor_invocation.
• extract_route_path_from_args() — unwraps value_argument (also handles the named value = "/x" form) before reading the path string.

No API or pipeline changes.

Verification

Minimal Kotlin + Java controllers indexed with the built binary:

• Before — Kotlin methods have empty route_method/route_path; Java works.
• After — createConnector → POST, getConnectorById → GET /{id}, deleteConnector → DELETE /{id}.

Added a handles_spring_kotlin regression test in tests/test_edge_types_probe.c. scripts/test.sh reports 5652 passed; the single failure is the pre-existing test_incremental RSS-budget assertion (environment-dependent, unrelated to this change).

Note (separate follow-up)

Class-level @RequestMapping base paths are still not merged with method-level paths (this affects Java too — a bare @PostMapping yields path /). I can address that in a separate PR.