perf(server): unblock event loop on rate-limit waits and markitdown

Two complementary changes to mitigate intermittent TLS handshake
timeouts and "notifications/cancelled: Bad Request" seen against the
single-worker uvicorn deployment.

1. bedesten rate-limiter back-pressure
   - Add optional ``max_wait`` to ``_TokenBucket.acquire``: if the next
     wait would exceed it, raise ``BedestenRateLimited`` immediately
     instead of sleeping. After a server-side 429 the bucket pauses for
     up to 30s; previously a queued request sat in ``asyncio.sleep``
     for that whole window, holding the worker slot and pushing the
     MCP client past its cancellation timeout.
   - ``search_bedesten_unified`` / ``get_bedesten_document_markdown``
     catch ``BedestenRateLimited`` and reuse the existing structured
     429-style response, so callers get a fast, clean retry signal.
   - Tunable via ``BEDESTEN_RATE_MAX_WAIT_S`` (default 8.0s).

2. Offload sync markitdown conversions to a thread
   - Every ``markitdown.convert*`` call site is now wrapped in
     ``asyncio.to_thread(...)`` across 14 modules (bedesten, yargitay,
     danistay, anayasa norm + bireysel, uyusmazlik, emsal, rekabet,
     gib, kvkk, sayistay, bddk, sigorta_tahkim, kik_v2). PDF / large
     HTML parsing was stalling the event loop for seconds, which on a
     single-worker deployment delayed every other in-flight request
     and queued new TLS handshakes until they timed out.

Verified locally:
- ``ast.parse`` + ``importlib.import_module`` on all 15 modified files
- ``mcp_server_main.create_app()`` constructs successfully
- New ``_TokenBucket.acquire(max_wait=...)`` smoke-tested across 6
  paths: capacity-available, no-arg backward compat, max_wait raise,
  max_wait wait+succeed, ``penalize_until`` + max_wait fast-raise.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

rekabet_mcp_module/client.py

@@ -1,5 +1,6 @@
 # rekabet_mcp_module/client.py
 
+import asyncio
 import httpx
 from bs4 import BeautifulSoup
 from typing import List, Optional, Tuple, Dict, Any
@@ -353,7 +354,7 @@ class RekabetKurumuApiClient:
                     total_pdf_pages = total_pdf_pages_from_extraction 
 
                     if single_page_pdf_bytes:
-                        markdown_for_requested_page = self._convert_pdf_bytes_to_markdown(single_page_pdf_bytes, str(pdf_url_to_report or full_landing_page_url))
+                        markdown_for_requested_page = await asyncio.to_thread(self._convert_pdf_bytes_to_markdown, single_page_pdf_bytes, str(pdf_url_to_report or full_landing_page_url))
                         if not markdown_for_requested_page:
                             error_message = (error_message or "") + f"; Could not convert page {page_number} of PDF to Markdown."
                     elif total_pdf_pages > 0 :