docs: add TS plugin internals documentation (#358)

* docs: add TS plugin internals documentation

Document the internal architecture of the TypeScript Language Service Plugin,
covering Volar.js virtual code generation, position mappings, the single-quote
span problem and its solution, linkedCodeMappings, and the language service proxy.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix(docs): preserve single quotes in ts-plugin-internals code blocks

Add docs/ts-plugin-internals.md to fmt.ignorePatterns in vite.config.ts
to prevent oxfmt from stripping single quotes in code blocks. Restore
the single-quoted property names that are essential to the document's
technical explanation.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* format

* docs: add note that document was generated by Claude Code

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* docs: reference ts-plugin-internals.md from CLAUDE.md

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore: replace CLAUDE.md symlink with @AGENTS.md reference

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* docs(ts-plugin): fix internals documentation

* docs: improve docs

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: mizdra

AGENTS.md

@@ -95,6 +95,11 @@ function myFunction() {
 - **Mapping**: An object that maintains the positional relationship between a `.d.ts` file and its corresponding .css file
   - Mapping enables language features such as Go to Definition, Find All References, Rename
 
+## Additional Documentation
+
+- [`docs/ts-plugin-internals.md`](./docs/ts-plugin-internals.md): Deep dive into the TS plugin internals
+  - Read this when working on `packages/ts-plugin` or `packages/core/src/dts-generator.ts` — especially when modifying Volar.js mappings, virtual code generation, or language service features (Go to Definition, Find References, Rename, etc.)
+
 ## Key Files
 
 - `packages/core/src/type.ts`: Main type definitions used by CSS Modules Kit

CLAUDE.md

@@ -0,0 +1 @@
+@AGENTS.md