fix(espn): fetch a window's edge months whole, cap chunk requests per process (#751)

- fetch_espn_date_chunks() asks for a window's partial edge month whole when the window covers ESPN_MONTH_COVER_MIN_DAYS (7) or more of its days, trimmed to the window by US Eastern start date. New espn_request_chunks().
- Chunk requests share one process-wide cap of ESPN_CHUNK_WORKERS (6) in flight.
- A new process starts as if a range had just been rejected, so it no longer spends a doomed 400 per window at start.
- Also: _eastern_zone() without try/except/pass (Codacy), and test_on_demand_live_and_restore reads the last on-demand state write rather than the last cache write (the font-usage publisher raced it; main CI had failed on it since #748).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test/test_fetch_service.py

@@ -670,14 +670,14 @@ class TestCallerIdentity:
         assert _counters(global_service, plugin="football-scoreboard")["requests"] == 1
 
     def test_espn_chunks_on_worker_threads_count_against_the_caller(self, global_service):
-        from src.common.espn_dates import espn_date_chunks, fetch_espn_date_chunks, parse_espn_date_range
+        from src.common.espn_dates import espn_request_chunks, fetch_espn_date_chunks, parse_espn_date_range
 
         session = FakeSession(lambda url, kw: make_response(body=b'{"events": []}', url=url))
         dates = "20260801-20261015"
         with plugin_scope("baseball-scoreboard"):
             fetch_espn_date_chunks(session, "https://site.api.espn.com/s/scoreboard",
                                    params={"dates": dates})
-        chunks = len(espn_date_chunks(*parse_espn_date_range(dates)))
+        chunks = len(espn_request_chunks(*parse_espn_date_range(dates)))
         assert chunks > 1
         assert len(session.calls) == chunks
         assert _counters(global_service, plugin="baseball-scoreboard")["requests"] == chunks