Send languageId 'typescriptreact' / 'javascriptreact' for .tsx / .jsx files (#1436)

* Fix: send languageId 'typescriptreact' / 'javascriptreact' for .tsx / .jsx

Without this, .tsx files are opened with languageId 'typescript', so
tsserver parses JSX as syntax errors and recovers by truncating the
enclosing symbol's range at the first multi-line JSX expression. The
resulting symptoms:

- find_symbol(name, include_body=True) on a React component returns a
  body that ends mid-component, hiding everything below.
- The same component shows up as multiple Method-kind symbols (one per
  call site) plus a separately-tracked Constant for the definition,
  because tsserver mistakes JSX-tag tokens for member access.

Reproducer (before fix, real-world TSX file):
  SidebarPDF range = [11:1-25:207]   (truncated at first JSX, line 25)
After fix:
  SidebarPDF range = [11:1-281:2]    (full body)

The base SolidLanguageServer._get_language_id_for_file is explicitly
designed for this — its docstring says "Override in subclasses to
return file-specific language IDs." This change just exercises that
hook for the React file extensions.

Adds a regression test + jsx_component.tsx fixture covering the same
arrow-function-with-multi-line-JSX-ternary pattern that triggers the
truncation in real codebases (see oraios/serena#1029 for an earlier
report whose root cause was not identified).

test/resources/repos/typescript/test_repo/jsx_component.tsx

@@ -0,0 +1,44 @@
+// Regression fixture: mirrors the real-world pattern that caused
+// languageId=typescript (instead of typescriptreact) to truncate symbol
+// ranges at the first multi-line JSX expression.
+
+import * as React from "react"
+
+type SectionProps = { title: string; emphasised?: boolean }
+
+function Section({ title, emphasised }: SectionProps) {
+  return emphasised ? (
+    <h1 style={{ color: "red" }}>{title}</h1>
+  ) : (
+    <h2 style={{ color: "gray" }}>{title}</h2>
+  )
+}
+
+export function JsxComponent({ heading, items }: { heading: string; items: string[] }) {
+  const renderHeader = (title: string) =>
+    title.length > 10 ? (
+      <Section title={title} emphasised />
+    ) : (
+      <Section title={title} />
+    )
+
+  // The truncation bug used to cut JsxComponent's range right around here,
+  // hiding everything below from find_symbol. Keep this comment so the
+  // regression test can assert the function body extends past it.
+  const renderItem = (item: string, idx: number) => (
+    <li key={idx} style={{ marginBottom: 4 }}>
+      {item}
+    </li>
+  )
+
+  return (
+    <div>
+      {renderHeader(heading)}
+      <ul>{items.map(renderItem)}</ul>
+    </div>
+  )
+}
+
+export function trailingHelper(): string {
+  return "this symbol is invisible to find_symbol when JsxComponent's range is truncated"
+}

test/resources/repos/typescript/test_repo/tsconfig.json

@@ -5,7 +5,8 @@
     "strict": true,
     "esModuleInterop": true,
     "forceConsistentCasingInFileNames": true,
-    "skipLibCheck": true
+    "skipLibCheck": true,
+    "jsx": "react"
   },
-  "include": ["**/*.ts"]
+  "include": ["**/*.ts", "**/*.tsx"]
 }