feat(moonraker): use buried/report as size/duration/layer fallback (Issue #102)

server/files/metadata returned broken placeholders (size: 1,
estimated_time: null) for any file that wasn't uploaded through the
bridge's own GCode store - e.g. prints started directly from Anycubic
Slicer Next.

Verified live against a real Kobra X (see memory
reference_buried_report_trigger.md) that the printer sends a
previously-unused MQTT topic, buried/report, exactly once per print
start - fires identically whether the print was started via Anycubic
Slicer Next or via OrcaSlicer/the bridge itself. It carries gcode_size,
estimate_duration, and total_layers: precisely the fields the metadata
endpoint was missing.

Add _on_buried() (registered alongside the existing file/report
callback) that caches the single most recent buried/report payload.
_build_file_metadata() now tries this cache - matched by task_name -
as a third fallback, between the existing GCodeStore lookup and the
final size:1 hardcoded placeholder. Ordering is deliberate: live
tracked-job state and the file's own GCodeStore row (if the file was
uploaded through the bridge) still take priority; buried/report only
fills the gap for files the bridge has no other record of.

Also surfaces the printer's own storage usage (storage_total_mb/
storage_used_mb from the same payload) in /api/state, previously not
exposed anywhere in the bridge.

Verified end-to-end against the real printer: after a print start,
server/files/metadata for that file returned real size (9573908),
estimated_time (3203s), and layer_count (497) instead of the
placeholders, and /api/state reported real storage_total_mb/
storage_used_mb.

tests/test_buried_report.py

@@ -0,0 +1,111 @@
+"""
+Tests für buried/report — das druckerseitige Analytics-Event, das einmal pro
+Druckstart feuert (verifiziert live gegen einen echten Kobra X, sowohl für
+Anycubic Slicer Next als auch für OrcaSlicer/die Bridge selbst). Liefert
+gcode_size/estimate_duration/total_layers, die server/files/metadata für
+Dateien außerhalb des eigenen GCodeStore sonst nicht hat (Issue #102).
+"""
+import pytest
+
+
+BURIED_PAYLOAD = {
+    "type": "buried",
+    "action": "PrintStart",
+    "code": 200,
+    "state": "done",
+    "data": {
+        "task_name": "Smileys_simple_plate(01)_PLA_0.2_16m39s.gcode",
+        "gcode_size": 644437,
+        "estimate_duration": 1264,
+        "total_layers": 8,
+        "storage_total": 6481,
+        "storage_used": 898,
+        "slicer": "OrcaSlicer",
+    },
+}
+
+
+def test_on_buried_populates_cache(client):
+    _, bridge = client
+    bridge._on_buried(BURIED_PAYLOAD)
+    assert bridge._buried_cache == {
+        "task_name": "Smileys_simple_plate(01)_PLA_0.2_16m39s.gcode",
+        "gcode_size": 644437,
+        "estimate_duration": 1264,
+        "total_layers": 8,
+    }
+
+
+def test_on_buried_populates_storage_state(client):
+    _, bridge = client
+    bridge._on_buried(BURIED_PAYLOAD)
+    assert bridge._state["storage_total_mb"] == 6481
+    assert bridge._state["storage_used_mb"] == 898
+
+
+def test_on_buried_ignores_payload_without_task_name(client):
+    _, bridge = client
+    bridge._buried_cache = None
+    bridge._on_buried({"type": "buried", "data": {"gcode_size": 123}})
+    assert bridge._buried_cache is None
+
+
+def test_build_file_metadata_uses_buried_fallback_for_unknown_file(client):
+    """A file not in the GCodeStore and not the currently-tracked job should
+    still get real size/estimated_time/layer_count from the buried cache."""
+    _, bridge = client
+    bridge._on_buried(BURIED_PAYLOAD)
+    meta = bridge._build_file_metadata("Smileys_simple_plate(01)_PLA_0.2_16m39s.gcode")
+    assert meta["size"] == 644437
+    assert meta["estimated_time"] == 1264
+    assert meta["layer_count"] == 8
+
+
+def test_build_file_metadata_ignores_buried_cache_for_different_file(client):
+    """The buried cache must only apply when task_name matches the queried
+    filename - otherwise it would leak the last print's data into an
+    unrelated query, the exact bug Issue #102 already fixed for live state."""
+    _, bridge = client
+    bridge._on_buried(BURIED_PAYLOAD)
+    meta = bridge._build_file_metadata("some_other_file.gcode")
+    assert meta["size"] == 1  # unchanged fallback, not leaked from buried cache
+    assert meta["estimated_time"] is None
+    assert meta["layer_count"] is None
+
+
+def test_build_file_metadata_prefers_gcodestore_over_buried(client):
+    """GCodeStore data (from the bridge's own upload) must win over the
+    buried cache when both are available for the same filename."""
+    _, bridge = client
+    bridge._on_buried(BURIED_PAYLOAD)
+    with bridge._store._lock:
+        bridge._store._conn.execute(
+            "INSERT INTO gcode_files (id, filename, path, size_bytes, uploaded_at, layer_count, est_print_time_sec) "
+            "VALUES (?,?,?,?,?,?,?)",
+            ("f1", "Smileys_simple_plate(01)_PLA_0.2_16m39s.gcode", "/tmp/f1", 999999, "2026-01-01T00:00:00Z", 42, 5000),
+        )
+        bridge._store._conn.commit()
+    meta = bridge._build_file_metadata("Smileys_simple_plate(01)_PLA_0.2_16m39s.gcode")
+    assert meta["size"] == 999999
+    assert meta["estimated_time"] == 5000
+    assert meta["layer_count"] == 42
+
+
+@pytest.mark.asyncio
+async def test_api_state_reports_storage_after_buried_report(client):
+    c, bridge = client
+    bridge._on_buried(BURIED_PAYLOAD)
+    resp = await c.get("/api/state")
+    assert resp.status == 200
+    data = await resp.json()
+    assert data["storage_total_mb"] == 6481
+    assert data["storage_used_mb"] == 898
+
+
+@pytest.mark.asyncio
+async def test_api_state_storage_defaults_to_zero(client):
+    c, _ = client
+    resp = await c.get("/api/state")
+    data = await resp.json()
+    assert data["storage_total_mb"] == 0
+    assert data["storage_used_mb"] == 0