feat(zig): add Zig language support with tree-sitter extraction

CHANGELOG.md

@@ -93,6 +93,7 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 - CodeGraph's MCP server now answers an agent's `resources/list` and `prompts/list` probes with an empty list instead of an error, clearing the `-32601` messages some clients (opencode, Codex) logged on connect. (#621)
 - Svelte and Vue components used through a barrel file — `export { default as Button } from './Button.svelte'` re-exported from an `index.ts` and imported elsewhere — are no longer falsely reported as having **0 callers**. CodeGraph now follows the default re-export all the way to the component and resolves the imports that `.svelte` / `.vue` files themselves use, so `codegraph_callers` and `codegraph_impact` see every place a component is used. This also covers components imported from another package in a workspace/monorepo (`@scope/ui/widgets`) and bare directory imports (`import { x } from './'`). Previously a live component consumed only through a barrel looked like dead code. Thanks @nakisen. (#629)
 - Components used in a Vue Single-File Component's `<template>` — `<MyButton />`, or the kebab-case `<my-button />` — are now indexed as usages, so `codegraph_callers` and `codegraph_impact` include components that appear only in another component's markup (including through a barrel re-export). Previously only a Vue component's `<script>` block was analyzed, so template-only usages were invisible. (#629)
+- Added Zig language support — parses `.zig` and `.zon` files with tree-sitter-zig, extracting functions, structs, enums, unions, opaque types, error sets, container fields, methods, variables, and `@import` references.
 - PHP: `include` / `require` / `include_once` / `require_once` of a static path now create a file→file dependency edge, so `codegraph_callers` and `codegraph_impact` follow includes in procedural / script-style PHP codebases — previously only namespace `use` statements became dependency edges. Dynamic includes (`include $var`, `require __DIR__ . '/x'`) are skipped. Thanks @atahan150 (#660).
 
 ## [0.9.9] - 2026-06-02