Record live performance gains and stabilize preview fixture

docs/PERFORMANCE.md

@@ -45,3 +45,21 @@ Baseline measured on production on 2026-10-02, before this change: longest run
 6,845 samples; median of three internal authenticated requests: dashboard HTML
 8 ms, run HTML 156 ms, run JSON 213 ms / 2,654 KiB uncompressed. These timings
 exclude network transfer, browser rendering and map tile downloads.
+
+After deployment and backfill on 2026-10-02: all 19 activities at analysis version
+1; rerun processed zero rows. Same longest run retained 6,845 raw samples and
+used 1,001 display route points. Persisted summary exactly matched a fresh
+full-resolution calculation. Median of three internal authenticated requests:
+
+| Response | Server time | Uncompressed size |
+| --- | ---: | ---: |
+| Dashboard HTML | 9 ms | 27 KiB |
+| Longest run HTML | 8 ms | 16 KiB |
+| Longest run JSON | 29 ms | 313 KiB |
+| Longest run route-only JSON | 7 ms | 23 KiB |
+
+Page and JSON requests issued zero raw sample/lap queries. HTTPS health returned
+HTTP 200 and `status: ok`; Dokku web and sync worker startup checks succeeded.
+The synthetic browser fixture verified dashboard replay, route colour switching
+and charts. Its in-memory SQLite server uses one request thread to avoid concurrent
+access to the shared SQLite connection.

scripts/preview-fixture.py

@@ -83,4 +83,4 @@ def preview_login():
 
 
 if __name__ == "__main__":
-    serve(app, host="127.0.0.1", port=5001)
+    serve(app, host="127.0.0.1", port=5001, threads=1)