docs: update CHANGELOG for extraction performance improvements

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CHANGELOG.md

@@ -29,6 +29,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
   queries, geometry columns).
 - **SOPS secrets** — `GEONAMES_USERNAME=padelnomics` and `CENSUS_API_KEY` added to both
   `.env.dev.sops` and `.env.prod.sops`.
+- **Crash-safe partial JSONL** — `utils.load_partial_results()` and `flush_partial_batch()`
+  provide a generic opt-in mechanism for incremental progress flushing during long extractions.
+  Any extractor processing items one-by-one can flush every N records and resume from a
+  `.partial.jsonl` sidecar file after a crash.
 - **Methodology page updated** — `/en/market-score` now documents both scores with:
   Two Scores intro section, component cards for each score (4 Marktreife + 5 Marktpotenzial),
   score band interpretations, expanded FAQ (7 entries). Section headings use the padelnomics
@@ -42,6 +46,19 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
   First "padelnomics Market Score" mention in each article template now links
   to the methodology page (hub-and-spoke internal linking).
 
+### Changed
+- **`EXTRACT_WORKERS` env var removed** — worker count is now derived from `PROXY_URLS` length
+  (one worker per proxy). No proxies → single-threaded. No manual tuning needed.
+- **Playtomic tenants extractor** — parallel batch page fetching when proxies are configured.
+  Each page in a batch fires concurrently using its own session + proxy. Expected speedup:
+  ~2.5 min → ~15 s with 10 Webshare datacenter proxies.
+- **Playtomic availability extractor** — three performance changes:
+  1. No per-request `time.sleep()` on success when a proxy is active (throttle only when
+     running direct). Retry/backoff sleeps for 429 and 5xx responses are unchanged.
+  2. Worker count auto-detected from proxy count (drops `EXTRACT_WORKERS`).
+  3. True crash resumption via `.partial.jsonl` sidecar: progress flushed every 50 venues,
+     resume skips already-fetched venues and merges prior results into the final file.
+
 ### Fixed
 - **`datetime.utcnow()` deprecation warnings** — replaced all 94 occurrences
   across 22 files (source + tests) with `utcnow()` / `utcnow_iso()` helpers