feat(solidlsp): add Astro language server support (#2085)

* feat(solidlsp): add Astro language server support (T170)

* test(solidlsp): fix relative_paths type extraction in test_astro_basic

* refactor(solidlsp): replace asserts with explicit exceptions in Astro LSP

* docs(memories): document rule against assert in language server guide

* docs: add Astro language server documentation (README, docs, template, CHANGELOG)

* feat(solidlsp): implement dual-server architecture for Astro with companion TypeScript server (#2085)

- Implement companion AstroTypeScriptServer using @astrojs/ts-plugin for cross-file code intelligence between .ts and .astro components
- Route .ts/.js document symbols, definitions, references, and renames through companion TypeScript server
- Support two-way buffer edit forwarding between Astro LS and companion TS server
- Replace all assert statements with explicit SolidLSPException and FileNotFoundError
- Handle *.customData configuration requests for Volar HTML service
- Register .astro extension in src/serena/hooks.py
- Add test fixtures and tests for symbol retrieval and cross-file references from TypeScript to Astro components
- Update documentation and CHANGELOG

* fix(solidlsp): narrow astro_ls type to AstroLanguageServer in companion server test

* fix(solidlsp): prevent caching empty document symbols and poll initial compilation in Nextflow tests

test/conftest.py

@@ -313,6 +313,7 @@ _LANGUAGE_PYTEST_MARKERS: dict[LanguageServerId, list[MarkDecorator | Mark]] = {
     LanguageServerId.ANGULAR: [pytest.mark.angular],
     LanguageServerId.HTML: [pytest.mark.html],
     LanguageServerId.SCSS: [pytest.mark.scss],
+    LanguageServerId.ASTRO: [pytest.mark.astro],
 }