Add redirect tracking and analysis features

Database Schema:
- Added redirect_url VARCHAR(2048) to pages table
- Added redirect_count INT DEFAULT 0 to pages table
- Added index on redirect_count for faster queries

Configuration:
- Created Config class with typed constants (PHP 8.3+)
- MAX_REDIRECT_THRESHOLD = 3 (configurable warning threshold)
- MAX_CRAWL_DEPTH = 50
- CONCURRENCY = 10

Backend Changes:
- Crawler now tracks redirects using Guzzle's redirect tracking
- Extracts redirect history from response headers
- Records redirect count and final destination URL
- Guzzle configured with max 10 redirects and tracking enabled

API Endpoint:
- New endpoint: /api.php?action=redirects
- Analyzes redirect types (permanent 301/308 vs temporary 302/303/307)
- Identifies excessive redirects (> threshold)
- Returns statistics and detailed redirect information

Frontend Changes:
- Added "Redirects" tab with:
  * Statistics overview (Total, Permanent, Temporary, Excessive)
  * Detailed table showing all redirects
  * Visual warnings for excessive redirects (yellow background)
  * Color-coded redirect counts (red when > threshold)
  * Status code badges (green for permanent, blue for temporary)

All quality checks pass:
- PHPStan Level 8: 0 errors
- PHPCS PSR-12: 0 errors

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

config/docker/init.sql

@@ -31,11 +31,14 @@ CREATE TABLE IF NOT EXISTS pages (
     meta_description TEXT,
     status_code INT,
     content_type VARCHAR(100),
+    redirect_url VARCHAR(2048),
+    redirect_count INT DEFAULT 0,
     crawled_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
     FOREIGN KEY (crawl_job_id) REFERENCES crawl_jobs(id) ON DELETE CASCADE,
     INDEX idx_crawl_job (crawl_job_id),
     INDEX idx_url (url(255)),
     INDEX idx_status_code (status_code),
+    INDEX idx_redirect_count (redirect_count),
     UNIQUE KEY unique_job_url (crawl_job_id, url(255))
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;