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

tests/Framework/Mail/MailerTest.php

@@ -12,6 +12,7 @@ use App\Framework\Mail\Message;
 use App\Framework\Mail\Testing\MockTransport;
 use App\Framework\Mail\TransportResult;
 use App\Framework\Queue\Queue;
+use App\Framework\Queue\ValueObjects\JobPayload;
 
 describe('Mailer', function () {
     beforeEach(function () {
@@ -241,17 +242,39 @@ class MailTestQueue implements Queue
 
     private array $jobs = [];
 
-    public function push(object $job): void
+    public function push(JobPayload $payload): void
     {
         $this->used = true;
-        $this->jobs[] = $job;
+        $this->jobs[] = $payload;
     }
 
-    public function pop(): ?object
+    public function pop(): ?JobPayload
     {
         return array_shift($this->jobs);
     }
 
+    public function peek(): ?JobPayload
+    {
+        return $this->jobs[0] ?? null;
+    }
+
+    public function size(): int
+    {
+        return count($this->jobs);
+    }
+
+    public function clear(): int
+    {
+        $count = count($this->jobs);
+        $this->jobs = [];
+        return $count;
+    }
+
+    public function getStats(): array
+    {
+        return ['size' => count($this->jobs)];
+    }
+
     public function wasUsed(): bool
     {
         return $this->used;