feat(core): add Swift tree-sitter support

[KumamuKuma]

Summary

• add a workspace-vendored tree-sitter Swift WASM package and wire swiftConfig into the tree-sitter loader
• add SwiftExtractor coverage for Swift type containers, functions/methods, visibility, imports/exports, and call graph extraction
• add Swift import-map resolution for SwiftPM modules, including Package.swift target paths, so Swift test targets can connect to source targets

Scope

This PR is intentionally Swift-only. The Windows CI skill-test fix is kept separate in #538.

CI note

Ubuntu passes on this branch. The current Windows failure is caused by existing Windows skill-test issues in main that are fixed by #538, not by the Swift extractor changes. Recommended order: merge #538 first, then update/rebase this PR so #537 can rerun on the fixed Windows CI baseline.

Why

Swift files were previously scanned as code but had no tree-sitter grammar/extractor, so .swift files produced empty structural analysis and no useful graph nodes/edges. This addresses the Swift side of #226 and follows the workspace-vendored WASM pattern used after #435, avoiding the third-party bundle approach from #344.

Local tests

• corepack pnpm --filter @understand-anything/core build
• corepack pnpm --filter @understand-anything/core test
• corepack pnpm exec vitest run tests/skill/understand/test_extract_import_map.test.mjs tests/skill/understand/test_scan_project.test.mjs

[Lum1104]

Thanks for your PRs, merged them. Awesome!