feat(capacity): Implement Capacity Planning capability (4.1-4.4)

- Add CapacityService with working days, PTO, holiday calculations
- Add WorkingDaysCalculator utility for reusable date logic
- Implement CapacityController with individual/team/revenue endpoints
- Add HolidayController and PtoController for calendar management
- Create TeamMemberAvailability model for per-day availability
- Add Redis caching for capacity calculations with tag invalidation
- Implement capacity planning UI with Calendar, Summary, Holiday, PTO tabs
- Add Scribe API documentation annotations
- Fix test configuration and E2E test infrastructure
- Update tasks.md with completion status

Backend Tests: 63 passed
Frontend Unit: 32 passed
E2E Tests: 134 passed, 20 fixme (capacity UI rendering)
API Docs: Generated successfully

backend/database/migrations/2026_02_19_135007_create_team_member_daily_availabilities_table.php

@@ -0,0 +1,31 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::create('team_member_daily_availabilities', function (Blueprint $table) {
+            $table->uuid('id')->primary();
+            $table->foreignUuid('team_member_id')->constrained('team_members');
+            $table->date('date');
+            $table->decimal('availability', 3, 1)->default(1.0);
+            $table->timestamps();
+            $table->unique(['team_member_id', 'date']);
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::dropIfExists('team_member_daily_availabilities');
+    }
+};