fix: arcade images in armsx2 are found by content

FindArcadeBiosFor (pcsx2/ps2/BiosTools.cpp:366-419 at 7f914418) scans the BIOS folder for 2 to 8 MB COH-H images and picks by EXTINFO serial, never by name. r27v1602f.8g, r27v1602f.7d and COH-H31000.BIN now carry found_by: content, and the truth no longer says armsx2 opens those names. The guard covers the 2 MB lower bound.

emulators/armsx2.yml

@@ -182,6 +182,7 @@ files:
     source_ref: "source pcsx2/ps2/BiosTools.cpp:17-18, source pcsx2/ps2/BiosTools.cpp:81-211, source pcsx2/ps2/BiosTools.cpp:421-450, source pcsx2/ps2/BiosTools.cpp:505-565"
 
   - name: r27v1602f.8g
+    found_by: content
     path: pcsx2/bios/r27v1602f.8g
     standalone_path: bios/r27v1602f.8g
     agnostic: true
@@ -201,6 +202,7 @@ files:
     source_ref: "source pcsx2/ps2/BiosTools.cpp:282-299, source pcsx2/ps2/BiosTools.cpp:331-419, source pcsx2/ps2/BiosTools.cpp:505-529, source pcsx2/VMManager.cpp:895-899, source pcsx2/VMManager.cpp:1847-1871, source pcsx2/VMManager.cpp:2123-2130"
 
   - name: r27v1602f.7d
+    found_by: content
     path: pcsx2/bios/r27v1602f.7d
     standalone_path: bios/r27v1602f.7d
     agnostic: true
@@ -217,6 +219,7 @@ files:
     source_ref: "source pcsx2/ps2/BiosTools.cpp:176-183, source pcsx2/ps2/BiosTools.cpp:331-419, source pcsx2/ps2/BiosTools.cpp:505-529"
 
   - name: COH-H31000.BIN
+    found_by: content
     path: pcsx2/bios/COH-H31000.BIN
     standalone_path: bios/COH-H31000.BIN
     agnostic: true

tests/test_audit_regressions.py

@@ -7079,6 +7079,9 @@ class Ps2BiosImagesAreFoundByContent(unittest.TestCase):
     opens, and the RetroDECK export added it as a required file."""
 
     def test_every_ps2_image_scan_is_marked(self):
+        """ARMSX2's arcade scan takes 2 to 8 MB COH-H images by their EXTINFO
+        serial (BiosTools.cpp:366-419 at 7f914418): r27v1602f.8g read as a
+        name armsx2 opens on six platforms."""
         import yaml
 
         from validation import opens_by_name
@@ -7090,7 +7093,7 @@ class Ps2BiosImagesAreFoundByContent(unittest.TestCase):
                 continue
             for entry in profile.get("files") or []:
                 if (
-                    entry.get("min_size") == 4194304
+                    entry.get("min_size") in (2097152, 4194304)
                     and entry.get("max_size") == 8388608
                     and opens_by_name(entry, profile)
                 ):