fix: say which cores find their BIOS by content

DuckStation (bios.cpp:208, 397-427), SwanStation (host_interface.cpp:
136-194), rustation (lib.rs:107-160), FS-UAE (rommgr.cpp:92-151),
ares (firmware.cpp:116-136) and Altirra (uifirmwarescan.cpp:29-113)
scan a folder and identify firmware by hash; Ymir does in its
standalone build only. FS-UAE still opens rom.key by name
(rommgr.cpp:1397-1498). The export then stops writing their labels
into platform lists: Batocera's psx block goes from 106 entries to 10,
and System.dat's scph5000.bin keeps its own hashes.

emulators/altirra.yml

@@ -10,6 +10,7 @@ profiled_date: "2026-08-11"
 core_version: "4.40"
 display_name: "Atari - 400/800/1200XL/XL/XE/XEGS/5200 (Altirra)"
 cores: [altirra]
+found_by: content
 systems: [atari-400-800, xegs, atari-5200]
 
 # Altirra emulates the Atari 400/800, 1200XL, 600XL/800XL, 130XE, XEGS and 5200.

emulators/ares.yml

@@ -8,6 +8,7 @@ core_version: "v147"
 display_name: "ares"
 cores: [ares]
 mode: standalone
+found_by: content
 systems:
   - arcade
   - atari-2600

emulators/duckstation.yml

@@ -9,6 +9,7 @@ source_commit: "4122fed9ad3e6e5c2ecf1516cd51675a5931623e"
 core_version: "v0.1"
 display_name: "Sony - PlayStation (DuckStation)"
 cores: [duckstation]
+found_by: content
 systems: [sony-playstation]
 bios_size: 524288  # 0x80000 (512 KB), also accepts PS2 (4 MB) and PS3 (0x3E66F0)
 verification: md5

emulators/fsuae.yml

@@ -9,6 +9,7 @@ core_version: "v5.0.7"
 display_name: "Commodore - Amiga (FS-UAE)"
 cores:
   - fsuae
+found_by: content
 systems:
   - amiga
 
@@ -151,6 +152,7 @@ files:
 
   - name: "rom.key"
     system: amiga
+    found_by: name
     required: false
     mode: both
     note: "Cloanto Amiga Forever decryption key. Enables encrypted ROM loading."

emulators/rustation.yml

@@ -9,6 +9,7 @@ upstream_commit: "1daf4faaade3c0fd1e9deace8e309e91303f1b46"
 core_version: "v1"
 display_name: "Sony - PlayStation (Rustation)"
 cores: [rustation]
+found_by: content
 systems: [sony-playstation]
 
 notes: >

emulators/swanstation.yml

@@ -8,6 +8,7 @@ source_commit: "b6c30a7b270a3f68ac41f268eafdfa678d17dea2"
 core_version: "v0.1"
 display_name: "Sony - PlayStation (SwanStation)"
 cores: [swanstation]
+found_by: content
 systems: [sony-playstation]
 notes: |
   Fork of DuckStation maintained by the libretro community after stenzek removed

emulators/ymir.yml

@@ -15,6 +15,7 @@ core_version:
 display_name: "Sega - Saturn (Ymir)"
 cores:
   - ymir
+found_by: {standalone: content}
 systems:
   - sega-saturn