ocaml/zig: no tags.scm — symbols come from the node-kind walker fallback, call edges are absent

[Frankie-Xu]

Status

OCaml (.ml/.mli) and Zig (.zig) are already registered in the breadth-tier GENERIC_LANGS table, but they have no vendored src/graph/queries/<lang>.scm. generic.ts says so explicitly:

These ship a tags.scm (calls + symbols); ocaml/zig have none and use the node-kind walker fallback (symbols only) — still one row, zero query.

The walker mints symbols from node-kind suffixes. It does not emit @reference.call, so graft callers on these languages has no edges to walk — same-file calls never resolve.

This is the same hole Dart had before #153 / #134: language is on the registry, grammar warms, but without a tags query the graph is symbols-only.

Plan

Two independent PRs, each adding one language the way #153 added Dart (query + generic-extract fixture; drop-not-guess — only AST shapes confirmed against the WASM grammar):

1. OCaml — ocaml.scm: @definition.function (let / let rec with a parameter, or fun body), @definition.module, @definition.type, @reference.call on application_expression. No infix/|>/@@ (noisy; not a call node).
2. Zig — zig.scm: function_declaration, const+struct_declaration, named test_declaration, call_expression.

Each PR: one .scm + tests + the generic.ts comment line for that language. No registry-row changes (both langs are already registered).

I'll follow up with the PRs.

[Frankie-Xu]

Follow-up PRs (independent branches, same pattern as Dart #153):

• OCaml tags.scm: feat(graph): add OCaml tags.scm — call edges for the breadth tier #200
• Zig tags.scm: feat(graph): add Zig tags.scm — call edges for the breadth tier #201

Both npm test green (884/884). The one-line generic.ts comment will conflict between them; after both merge it can drop the walker-fallback note.