fix(labels): replace incorrect ams_30x15 preset with correct AMS holder sizes (#1426)

Reporter — the same person who originally requested the labels
  feature in #809 — discovered that the ams_30x15 preset's 30x15 mm
  dimension didn't actually fit any variant of the MakerWorld AMS
  Filament Label Holder (model 752566) it advertised. Two new
  presets replace it:

  - ams_holder_74x33 (74 x 33 mm) matches the printable label STL
    bundled in the MakerWorld project
  - ams_holder_75x55 (75 x 55 mm) fits the cardstock-insert variant
    the reporter validated on bench

  Both cross the 20 mm height threshold so they land in the roomy
  layout branch — swatch on the left, QR on the right, multi-line
  text (brand, material, hex code, spool ID) in the middle. The
  old 30x15 mm preset couldn't fit a QR code; the new ones do.

  No DB migration: the preset name was never persisted. Callers
  scripting the old ams_30x15 value get a clean 422 at the route's
  Literal validator with the new valid values listed.

  i18n: replaced inventory.labels.templates.ams.{label,hint} with
  amsHolderSmall and amsHolderLarge across all 8 locales with real
  translations; parity guard cleaned of the stale English-fallback
  cognate entries. Parity holds at 4856 leaves per locale.

  Tests: backend label renderer + integration tests cover both new
  presets; LabelTemplatePickerModal test updated for the 6-button
  grid and the new template value in the API-call assertion.

backend/tests/integration/test_labels.py

@@ -66,7 +66,13 @@ class TestLocalInventoryLabels:
     @pytest.mark.integration
     async def test_all_four_templates_succeed(self, async_client: AsyncClient, spool_factory):
         s = await spool_factory()
-        for template in ("ams_30x15", "box_62x29", "avery_5160", "avery_l7160"):
+        for template in (
+            "ams_holder_74x33",
+            "ams_holder_75x55",
+            "box_62x29",
+            "avery_5160",
+            "avery_l7160",
+        ):
             resp = await async_client.post(
                 "/api/v1/inventory/labels",
                 json={"spool_ids": [s.id], "template": template},
@@ -100,7 +106,7 @@ class TestLocalInventoryLabels:
         s = await spool_factory()
         resp = await async_client.post(
             "/api/v1/inventory/labels",
-            json={"spool_ids": [s.id, 99999], "template": "ams_30x15"},
+            json={"spool_ids": [s.id, 99999], "template": "ams_holder_74x33"},
         )
         assert resp.status_code == 404
         assert "99999" in resp.text

backend/tests/unit/services/test_label_renderer.py

@@ -6,7 +6,14 @@ import pytest
 
 from backend.app.services.label_renderer import LabelData, render_labels
 
-ALL_TEMPLATES = ("ams_30x15", "box_40x30", "box_62x29", "avery_5160", "avery_l7160")
+ALL_TEMPLATES = (
+    "ams_holder_74x33",
+    "ams_holder_75x55",
+    "box_40x30",
+    "box_62x29",
+    "avery_5160",
+    "avery_l7160",
+)
 
 
 def _sample(spool_id: int = 1, **overrides) -> LabelData:
@@ -58,7 +65,7 @@ def test_missing_optional_fields_does_not_crash():
             deeplink_url="https://example.test/inventory?spool=42",
         )
     ]
-    pdf = render_labels("ams_30x15", data)
+    pdf = render_labels("ams_holder_74x33", data)
     assert pdf.startswith(b"%PDF")
 
 
@@ -74,7 +81,7 @@ def test_long_strings_are_truncated_not_overflowed():
     long_brand = "A" * 200
     long_name = "B" * 300
     data = [_sample(brand=long_brand, name=long_name)]
-    pdf = render_labels("ams_30x15", data)
+    pdf = render_labels("ams_holder_74x33", data)
     assert pdf.startswith(b"%PDF")
 
 
@@ -121,9 +128,10 @@ def _render_uncompressed(template, data):
     from backend.app.services.label_renderer import _draw_label  # noqa: PLC0415
 
     # Mirror the page-size choice from render_labels but force pageCompression=0.
-    if template in ("ams_30x15", "box_40x30", "box_62x29"):
+    if template in ("ams_holder_74x33", "ams_holder_75x55", "box_40x30", "box_62x29"):
         sizes = {
-            "ams_30x15": (30.0, 15.0),
+            "ams_holder_74x33": (74.0, 33.0),
+            "ams_holder_75x55": (75.0, 55.0),
             "box_40x30": (40.0, 30.0),
             "box_62x29": (62.0, 29.0),
         }
@@ -167,9 +175,9 @@ def _render_uncompressed(template, data):
 def test_ams_template_actually_renders_text():
     """Regression: the first cut of the AMS-holder layout produced labels with
     only swatch + QR and no text at all because the side-by-side layout left
-    <5 mm for the text column. The redesign drops the QR on this template and
-    gives the right side to brand + material + spool ID. This pins that the
-    rendered PDF contains all three fields.
+    <5 mm for the text column. The current AMS templates use the roomy layout
+    (swatch + QR + multi-line text); this pins that the rendered PDF contains
+    brand + material + spool ID for the smaller AMS preset.
     """
     data = [
         LabelData(
@@ -182,7 +190,7 @@ def test_ams_template_actually_renders_text():
             deeplink_url="https://example.test/inventory?spool=42",
         )
     ]
-    pdf = _render_uncompressed("ams_30x15", data)
+    pdf = _render_uncompressed("ams_holder_74x33", data)
     assert b"Polymaker" in pdf, "AMS template must render the brand"
     assert b"PLA" in pdf, "AMS template must render the material"
     # The bracketed-hash style is what the renderer uses for the spool ID;