Add captcha bypass, retry logic, and search improvements

[thumpersecure]

• Add captcha/block detection: scans responses for captcha indicators
  (recaptcha, hcaptcha, Cloudflare challenges, rate limit pages) and
  retries with exponential backoff and fresh headers
• Add request_with_retry() wrapper with configurable max retries,
  exponential backoff, and Retry-After header support
• Add DuckDuckGo HTML search fallback: when the Instant Answer API
  returns few/no results (common for phone numbers), falls back to
  scraping html.duckduckgo.com/html/ for actual web results
• Add adaptive rate limiting (AdaptiveRateLimiter): automatically
  increases delays when blocks are detected and decreases on sustained
  success, replacing the fixed 3-5s random delay
• Add requests.Session with connection pooling for better performance
  and less suspicious traffic patterns
• Improve request headers: add Sec-Fetch-*, Accept-Encoding with br,
  randomized Accept-Language, optional Referer rotation, and separate
  API-tuned headers (get_api_headers)
• Add result deduplication across all format groups by normalized URL
• Fix mismatched parenthesis in phone format generation: replace the
  buggy "(215) 555-1234)" format with dot-separated "215.555.1234"
• Update User-Agent strings to Chrome 122, Firefox 123, Safari 17.2
• Apply all improvements to telespotx.py async variant (v0.2-alpha):
  async_request_with_retry(), captcha detection, DDG HTML fallback,
  result deduplication, improved headers