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/SmartLink/ValueObjects/ClickId.php

@@ -0,0 +1,45 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Domain\SmartLink\ValueObjects;
+
+use App\Framework\DateTime\Clock;
+use App\Framework\Ulid\Ulid;
+
+final readonly class ClickId
+{
+    private function __construct(
+        private string $value
+    ) {
+        if (!Ulid::isValid($value)) {
+            throw new \InvalidArgumentException('Invalid Click ID format');
+        }
+    }
+
+    public static function generate(Clock $clock): self
+    {
+        $ulid = new Ulid($clock);
+        return new self($ulid->__toString());
+    }
+
+    public static function fromString(string $value): self
+    {
+        return new self($value);
+    }
+
+    public function toString(): string
+    {
+        return $this->value;
+    }
+
+    public function equals(self $other): bool
+    {
+        return $this->value === $other->value;
+    }
+
+    public function __toString(): string
+    {
+        return $this->value;
+    }
+}