Feature/multi printer support (#12)

* Initial implementation of multi-printer support.

* Always show device dropdown and add bambu_diagnose for multi-printer troubleshooting.

* Add multi-AMS support: per-unit snapshot/usage tracking, grouped dashboard panels with real type labels, and dual-nozzle card UX fixes. Fixes a real-world AMS info-code parsing bug found by inspecting live H2C data.

* Add Vortek hotend rack tracking: per-SN registry with slot mapping confirmed against live MQTT capture, plus a fallback for non-inductive nozzles (e.g. H2C's fixed left nozzle) shown read-only without fabricated identity. New dashboard card hides entirely on printers with no Vortek/nozzle-info data at all.

tests/test_diagnostics.py

@@ -0,0 +1,68 @@
+import pytest
+
+from bambu_run.diagnostics import redact_diagnostics, build_diagnostics_report
+
+
+def test_redacts_password_and_token_like_keys():
+    data = {"BAMBU_PASSWORD": "hunter2", "access_token": "abc123", "ok": "fine"}
+
+    redacted = redact_diagnostics(data)
+
+    assert redacted["BAMBU_PASSWORD"] == "***REDACTED***"
+    assert redacted["access_token"] == "***REDACTED***"
+    assert redacted["ok"] == "fine"
+
+
+def test_masks_known_identifier_keys_partially():
+    data = {"dev_id": "31B8BP592601478", "tray_uuid": "EE37828FA8844DE1AB12"}
+
+    redacted = redact_diagnostics(data)
+
+    assert redacted["dev_id"] == "31B8...1478"
+    assert redacted["tray_uuid"] == "EE37...AB12"
+
+
+def test_short_identifier_values_fully_masked():
+    data = {"dev_id": "short"}
+
+    redacted = redact_diagnostics(data)
+
+    assert redacted["dev_id"] == "***"
+
+
+def test_recurses_into_nested_structures():
+    data = {"devices": [{"dev_id": "31B8BP592601478", "name": "RNL-H2C"}]}
+
+    redacted = redact_diagnostics(data)
+
+    assert redacted["devices"][0]["dev_id"] == "31B8...1478"
+    assert redacted["devices"][0]["name"] == "RNL-H2C"
+
+
+def test_no_redact_passthrough_keeps_original_values():
+    data = {"dev_id": "31B8BP592601478", "BAMBU_PASSWORD": "hunter2"}
+
+    result = redact_diagnostics(data, redact=False)
+
+    assert result == data
+
+
+def test_build_diagnostics_report_structure():
+    devices = [{"dev_id": "SERIAL-A", "name": "Printer A", "dev_product_name": "H2C"}]
+    raw_payloads = {"SERIAL-A": {"device": {"extruder": {"info": []}}}}
+
+    report = build_diagnostics_report(devices, raw_payloads)
+
+    assert report["device_count"] == 1
+    assert "generated_at" in report
+    assert report["devices"][0]["device_info"]["dev_id"] == "SERIAL-A"
+    assert report["devices"][0]["raw_mqtt_payload"] == {"device": {"extruder": {"info": []}}}
+
+
+def test_build_diagnostics_report_handles_missing_payload():
+    devices = [{"dev_id": "SERIAL-A", "name": "Printer A"}]
+
+    report = build_diagnostics_report(devices, raw_payloads={})
+
+    assert report["devices"][0]["raw_mqtt_payload"] is None
+    assert report["devices"][0]["note"] == "No MQTT data received within the listen window."