Restore AddHtmlShellTemplates migration with copyright symbol fix

- Restored email.html-shell.start and email.html-shell.end templates to InitialSchema migration
- Fixed copyright symbol: changed © to © HTML entity (avoids encoding issues in database)
- These templates wrap plain text email bodies in proper HTML structure
- Migration runs after InitialSchema, seeding the HTML wrapper templates

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Apis/email-data/Migrations/20260601145256_AddHtmlShellTemplates.Designer.cs

@@ -1,4 +1,4 @@
-// <auto-generated />
+// <auto-generated />
 using System;
 using Email.Data;
 using Microsoft.EntityFrameworkCore;
@@ -63,6 +63,7 @@ namespace Email.Data.Migrations
 
                 b.ToTable("Templates", "email");
             });
+
             #pragma warning restore 612, 618
         }
     }

Apis/email-data/Migrations/20260601145256_AddHtmlShellTemplates.cs

@@ -1,4 +1,4 @@
-using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Migrations;
 using Email.Data;
 
 #nullable disable
@@ -22,7 +22,7 @@ namespace Email.Data.Migrations
             migrationBuilder.InsertData(
                 table: "Templates",
                 columns: new[] { "Key", "Language", "Value", "Description" },
-                values: new object[] { "email.html-shell.end", "*", "        </div>\n        <div class=\"email-footer\">\n            <p>© 2026 MyAi.ro. All rights reserved.</p>\n        </div>\n    </div>\n</body>\n</html>\n", "Closing HTML wrapper for branded emails (footer and closing tags)" },
+                values: new object[] { "email.html-shell.end", "*", " </div>\n <div class=\"email-footer\">\n <p>&copy; 2026 MyAi.ro. All rights reserved.</p>\n </div>\n </div>\n</body>\n</html>\n", "Closing HTML wrapper for branded emails (footer and closing tags)" },
                 schema: MigrationConstants.SchemaName);
         }