feat(ocr): suppress uvicorn access logs for /metrics and /health

Adds a logging.Filter on uvicorn.access that drops records whose request
path is /metrics or /health. Each is hit on a tight schedule (Prometheus
scrape interval and Docker healthcheck), so unfiltered they dominate the
access log without carrying any information about real traffic.

Refs #652 (Nora's recommendation)

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

ocr-service/main.py

@@ -82,6 +82,23 @@ app = FastAPI(title="Familienarchiv OCR Service", lifespan=lifespan)
 Instrumentator(excluded_handlers=["/health", "/metrics"]).instrument(app).expose(app)
 
 
+class MetricsPathFilter(logging.Filter):
+    """Drop uvicorn.access entries for /metrics and /health to keep logs focused."""
+
+    _SUPPRESSED_PATHS = {"/metrics", "/health"}
+
+    def filter(self, record: logging.LogRecord) -> bool:
+        # uvicorn.access formats as: '%s - "%s %s HTTP/%s" %d'
+        if record.args and len(record.args) >= 3:
+            path = record.args[2]
+            if isinstance(path, str) and path in self._SUPPRESSED_PATHS:
+                return False
+        return True
+
+
+logging.getLogger("uvicorn.access").addFilter(MetricsPathFilter())
+
+
 @app.get("/health")
 def health():
     """Health endpoint — returns 200 only after models are loaded."""

ocr-service/test_metrics.py

@@ -442,3 +442,33 @@ async def test_ocr_models_ready_gauge_is_one_after_lifespan_startup(fresh_metric
          patch("main.load_spell_checker"):
         async with app.router.lifespan_context(app):
             assert fresh_metrics.ocr_models_ready._value.get() == 1.0
+
+
+def test_uvicorn_access_log_filter_skips_metrics_path():
+    """The MetricsPathFilter drops uvicorn.access log records that target /metrics."""
+    import logging as _logging
+    from main import MetricsPathFilter
+
+    filt = MetricsPathFilter()
+    metrics_record = _logging.LogRecord(
+        name="uvicorn.access", level=_logging.INFO, pathname="", lineno=0,
+        msg='%s - "%s %s HTTP/%s" %d',
+        args=("127.0.0.1:1234", "GET", "/metrics", "1.1", 200),
+        exc_info=None,
+    )
+    health_record = _logging.LogRecord(
+        name="uvicorn.access", level=_logging.INFO, pathname="", lineno=0,
+        msg='%s - "%s %s HTTP/%s" %d',
+        args=("127.0.0.1:1234", "GET", "/health", "1.1", 200),
+        exc_info=None,
+    )
+    ocr_record = _logging.LogRecord(
+        name="uvicorn.access", level=_logging.INFO, pathname="", lineno=0,
+        msg='%s - "%s %s HTTP/%s" %d',
+        args=("127.0.0.1:1234", "POST", "/ocr", "1.1", 200),
+        exc_info=None,
+    )
+
+    assert filt.filter(metrics_record) is False
+    assert filt.filter(health_record) is False
+    assert filt.filter(ocr_record) is True