fix(linter): update no-unnecessary-template-expression docs and test case

apps/oxlint/fixtures/tsgolint/no-unnecessary-template-expression.ts

@@ -1,3 +1,4 @@
-const str1 = `Hello world`;
+const text = 'hello';
+const wrapped = `${text}`;
 
 export {};

apps/oxlint/src/snapshots/fixtures__tsgolint_--type-aware --silent@oxlint.snap

@@ -6,7 +6,7 @@ arguments: --type-aware --silent
 working directory: fixtures/tsgolint
 ----------
 
-Found 0 warnings and 50 errors.
+Found 0 warnings and 51 errors.
 Finished in <variable>ms on 45 files using 1 threads.
 ----------
 CLI result: LintFoundErrors

apps/oxlint/src/snapshots/fixtures__tsgolint_--type-aware@oxlint.snap

@@ -132,6 +132,14 @@ working directory: fixtures/tsgolint
  3 | }
    `----
 
+  x typescript-eslint(no-unnecessary-template-expression): Template literal expression is unnecessary and can be simplified.
+   ,-[no-unnecessary-template-expression.ts:2:18]
+ 1 | const text = 'hello';
+ 2 | const wrapped = `${text}`;
+   :                  ^^^^^^^
+ 3 | 
+   `----
+
   x typescript-eslint(no-unnecessary-type-arguments): This is the default value for this type parameter, so it can be omitted.
    ,-[no-unnecessary-type-arguments.ts:4:25]
  3 | }
@@ -388,7 +396,7 @@ working directory: fixtures/tsgolint
    :                   ^^^^^^^^
    `----
 
-Found 0 warnings and 50 errors.
+Found 0 warnings and 51 errors.
 Finished in <variable>ms on 45 files using 1 threads.
 ----------
 CLI result: LintFoundErrors

crates/oxc_linter/src/rules/typescript/no_unnecessary_template_expression.rs

@@ -8,46 +8,57 @@ pub struct NoUnnecessaryTemplateExpression;
 declare_oxc_lint!(
     /// ### What it does
     ///
-    /// This rule disallows unnecessary template literals.
+    /// Disallows unnecessary template expressions (interpolations) that can be simplified.
     ///
     /// ### Why is this bad?
     ///
-    /// Template literals should only be used when they are needed for string interpolation or multi-line strings. Using template literals when a simple string would suffice adds unnecessary complexity.
+    /// Template literals with substitution expressions that are unnecessary add complexity
+    /// without providing any benefit. Static string literal expressions or expressions that
+    /// are already strings can be simplified.
+    ///
+    /// Note: This rule does not flag template literals without substitution expressions.
+    /// For example, `` `hello` `` is allowed even though it could be written as `'hello'`.
     ///
     /// ### Examples
     ///
     /// Examples of **incorrect** code for this rule:
     /// ```ts
-    /// const str1 = `Hello world`;
+    /// // Static values can be incorporated into the surrounding template
+    /// const ab1 = `${'a'}${'b'}`;
+    /// const ab2 = `a${'b'}`;
     ///
-    /// const str2 = `42`;
+    /// const stringWithNumber = `${'1 + 1 = '}${2}`;
+    /// const stringWithBoolean = `${'true is '}${true}`;
     ///
-    /// const str3 = `true`;
+    /// // Expressions that are already strings can be rewritten without a template
+    /// const text = 'a';
+    /// const wrappedText = `${text}`;
     ///
-    /// // Template with only literal expressions
-    /// const str4 = `${'Hello'} ${'world'}`;
+    /// declare const intersectionWithString: string & { _brand: 'test-brand' };
+    /// const wrappedIntersection = `${intersectionWithString}`;
     /// ```
     ///
     /// Examples of **correct** code for this rule:
     /// ```ts
-    /// const str1 = 'Hello world';
+    /// // Static values incorporated into the template
+    /// const ab1 = `ab`;
     ///
-    /// const str2 = '42';
+    /// // Template with non-trivial interpolation
+    /// const name = 'world';
+    /// const greeting = `Hello ${name}!`;
     ///
-    /// const str3 = 'true';
+    /// // Template with expression
+    /// const result = `Result: ${1 + 2}`;
     ///
-    /// // Template with variable interpolation
-    /// const name = 'world';
-    /// const str4 = `Hello ${name}`;
+    /// // Simple strings don't need templates
+    /// const text = 'a';
+    /// const wrappedText = text;
     ///
-    /// // Multi-line string
+    /// // Multi-line strings are fine
     /// const multiline = `
     ///   Hello
     ///   world
     /// `;
-    ///
-    /// // Template with expression
-    /// const str5 = `Result: ${1 + 2}`;
     /// ```
     NoUnnecessaryTemplateExpression(tsgolint),
     typescript,