docs: consolidate documentation into organized structure

- Move 12 markdown files from root to docs/ subdirectories
- Organize documentation by category:
  • docs/troubleshooting/ (1 file)  - Technical troubleshooting guides
  • docs/deployment/      (4 files) - Deployment and security documentation
  • docs/guides/          (3 files) - Feature-specific guides
  • docs/planning/        (4 files) - Planning and improvement proposals

Root directory cleanup:
- Reduced from 16 to 4 markdown files in root
- Only essential project files remain:
  • CLAUDE.md (AI instructions)
  • README.md (Main project readme)
  • CLEANUP_PLAN.md (Current cleanup plan)
  • SRC_STRUCTURE_IMPROVEMENTS.md (Structure improvements)

This improves:
✅ Documentation discoverability
✅ Logical organization by purpose
✅ Clean root directory
✅ Better maintainability

src/Domain/Media/Migrations/CreateImagesTableWithSchema.php

@@ -16,7 +16,7 @@ final class CreateImagesTableWithSchema implements Migration
     {
         $schema = new Schema($connection);
 
-        $schema->create('images', function (Blueprint $table) {
+        $schema->createIfNotExists('images', function (Blueprint $table) {
             $table->ulid('ulid')->primary();
             $table->string('filename', 255);
             $table->string('original_filename', 255);