Support msg({...}) descriptor form and add auto-fix

- Allow msg() function call form: _(msg({message: 'Hello'}))
- Add auto-fix for string literals: _('Bad') -> _(msg`Bad`)
- Add auto-fix for untagged templates: _(`Bad`) -> _(msg`Bad`)
- No auto-fix for variables/function calls (not safely fixable)

https://claude.ai/code/session_01JMXXPUgAHiSBGmfGwUojKy

eslint/lingui-msg-rule.js

@@ -11,9 +11,10 @@ module.exports = {
         'Enforce that Lingui _() function is called with msg`` template literal or plural/select macros',
       recommended: true,
     },
+    fixable: 'code',
     messages: {
       missingMsg:
-        'Lingui _() must be called with msg`...` template literal or plural/select/selectOrdinal. Example: _(msg`Hello`)',
+        'Lingui _() must be called with msg`...` or msg({...}) or plural/select/selectOrdinal. Example: _(msg`Hello`)',
     },
     schema: [],
   },
@@ -21,11 +22,45 @@ module.exports = {
   create(context) {
     // Valid Lingui macro functions that can be passed to _()
     const VALID_MACRO_FUNCTIONS = new Set([
+      'msg',
       'plural',
       'select',
       'selectOrdinal',
     ])
 
+    /**
+     * Escape backticks and backslashes for template literal
+     */
+    function escapeForTemplateLiteral(str) {
+      return str.replace(/\\`/g, '`').replace(/`/g, '\\`')
+    }
+
+    /**
+     * Try to get a fixer for the given argument
+     * Returns null if we can't safely fix it
+     */
+    function getFixer(firstArg) {
+      const sourceCode = context.sourceCode ?? context.getSourceCode()
+
+      // Fix string literals: _('foo') -> _(msg`foo`)
+      if (firstArg.type === 'Literal' && typeof firstArg.value === 'string') {
+        const escaped = escapeForTemplateLiteral(firstArg.value)
+        return function (fixer) {
+          return fixer.replaceText(firstArg, 'msg`' + escaped + '`')
+        }
+      }
+
+      // Fix untagged template literals: _(`foo`) -> _(msg`foo`)
+      if (firstArg.type === 'TemplateLiteral') {
+        const text = sourceCode.getText(firstArg)
+        return function (fixer) {
+          return fixer.replaceText(firstArg, 'msg' + text)
+        }
+      }
+
+      return null
+    }
+
     return {
       CallExpression(node) {
         // Check if this is a call to _()
@@ -53,7 +88,7 @@ module.exports = {
           return
         }
 
-        // Valid: _(plural(...)), _(select(...)), _(selectOrdinal(...))
+        // Valid: _(msg(...)), _(plural(...)), _(select(...)), _(selectOrdinal(...))
         if (
           firstArg.type === 'CallExpression' &&
           firstArg.callee.type === 'Identifier' &&
@@ -63,9 +98,11 @@ module.exports = {
         }
 
         // Everything else is invalid
+        const fix = getFixer(firstArg)
         context.report({
           node,
           messageId: 'missingMsg',
+          fix,
         })
       },
     }