feat(core,fuse,gui): find photos that look alike

The duplicate finder gains an Exact / Similar switch. Similar asks the
daemon for PhotoSimilar, which starts a background pass that hashes the
thumbnail of every shot not hashed yet and replies at once with the sets
found so far and how far hashing has got. The dialog shows a progress bar
and asks again until the pass is done, then lists the sets.

The pass takes thumbnails from the server only: a photo without one is
skipped for the run instead of downloaded whole, and the dialog says how
many photos could not be compared. Decoding and hashing are spread over
the machine's cores.

Every similar photo starts ticked Keep, since photos that look alike can
be different shots. A similar photo stands for its whole shot, so one not
kept goes to Trash with the rest of its shot.

po/nl.po

@@ -5,7 +5,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: proton-drive-linux 2.1.0\n"
 "Report-Msgid-Bugs-To: https://github.com/narrrl/proton-drive-linux/issues\n"
-"POT-Creation-Date: 2026-09-28 03:11+0200\n"
+"POT-Creation-Date: 2026-09-28 03:33+0200\n"
 "PO-Revision-Date: 2026-09-23 12:00+0200\n"
 "Last-Translator: Proton Drive for Linux contributors\n"
 "Language-Team: Dutch\n"
@@ -312,7 +312,6 @@ msgstr "Hernoemen"
 #: crates/pdfs-gui/src/app/pages/browser.rs:414
 #: crates/pdfs-gui/src/app/pages/browser.rs:1306
 #: crates/pdfs-gui/src/app/pages/browser.rs:1338
-#: crates/pdfs-gui/src/app/pages/duplicates.rs:24
 #: crates/pdfs-gui/src/app/pages/photos.rs:607
 #: crates/pdfs-gui/src/app/pages/photos.rs:2063
 #: crates/pdfs-gui/src/app/pages/photos.rs:2067
@@ -764,7 +763,7 @@ msgstr "Kon het album niet aanmaken"
 #: crates/pdfs-gui/src/app/pages/devices.rs:532
 #: crates/pdfs-gui/src/app/pages/devices.rs:682
 #: crates/pdfs-gui/src/app/pages/devices.rs:912
-#: crates/pdfs-gui/src/app/pages/duplicates.rs:63
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:223
 #: crates/pdfs-gui/src/app/pages/locations.rs:342
 #: crates/pdfs-gui/src/app/pages/locations.rs:516
 #: crates/pdfs-gui/src/app/pages/locations.rs:739
@@ -1902,28 +1901,82 @@ msgstr "Identiteit overgenomen"
 msgid "Couldn't adopt that computer"
 msgstr "Kon die computer niet overnemen"
 
-#: crates/pdfs-gui/src/app/pages/duplicates.rs:15
-msgid "Looking for duplicates…"
-msgstr "Duplicaten zoeken…"
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:79
+msgctxt "duplicates"
+msgid "Exact"
+msgstr "Exact"
 
-#: crates/pdfs-gui/src/app/pages/duplicates.rs:42
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:80
+msgid "Photos stored more than once"
+msgstr "Foto's die meer dan eens zijn opgeslagen"
+
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:84
+msgctxt "duplicates"
+msgid "Similar"
+msgstr "Vergelijkbaar"
+
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:85
+msgid "Photos that look alike"
+msgstr "Foto's die op elkaar lijken"
+
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:102
 msgid "Duplicates"
 msgstr "Duplicaten"
 
-#: crates/pdfs-gui/src/app/pages/duplicates.rs:56
-#: crates/pdfs-gui/src/app/pages/duplicates.rs:62
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:151
+msgid "Looking for duplicates…"
+msgstr "Duplicaten zoeken…"
+
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:152
+msgid "Looking for similar photos…"
+msgstr "Vergelijkbare foto's zoeken…"
+
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:176
 msgid "Couldn't look for duplicates"
 msgstr "Kon niet naar duplicaten zoeken"
 
-#: crates/pdfs-gui/src/app/pages/duplicates.rs:69
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:177
+msgid "Couldn't look for similar photos"
+msgstr "Kon niet naar vergelijkbare foto's zoeken"
+
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:185
+msgid "Comparing photos…"
+msgstr "Foto's vergelijken…"
+
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:187
+msgid "Photos are compared by their thumbnails. The first time takes a while."
+msgstr "Foto's worden vergeleken aan de hand van hun miniaturen. De eerste keer duurt dat even."
+
+#. Translators: {done} and {total} are numbers of photos.
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:196
+#, rust-format
+msgid "{done} of {total}"
+msgstr "{done} van {total}"
+
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:233
 msgid "No duplicates"
 msgstr "Geen duplicaten"
 
-#: crates/pdfs-gui/src/app/pages/duplicates.rs:71
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:235
 msgid "Every photo in your library is stored once."
 msgstr "Elke foto in je bibliotheek is maar één keer opgeslagen."
 
-#: crates/pdfs-gui/src/app/pages/duplicates.rs:88
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:239
+msgid "No similar photos"
+msgstr "Geen vergelijkbare foto's"
+
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:241
+msgid "No two photos in your library look alike."
+msgstr "Er zijn geen twee foto's in je bibliotheek die op elkaar lijken."
+
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:263
+#, rust-format
+msgid "{n} photo couldn't be compared because it has no thumbnail yet."
+msgid_plural "{n} photos couldn't be compared because they have no thumbnail yet."
+msgstr[0] "{n} foto kon niet worden vergeleken omdat die nog geen miniatuur heeft."
+msgstr[1] "{n} foto's konden niet worden vergeleken omdat ze nog geen miniatuur hebben."
+
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:286
 msgid ""
 "These photos are stored more than once. The copies you don't keep move to "
 "Trash, where you can restore them."
@@ -1931,21 +1984,40 @@ msgstr ""
 "Deze foto's zijn meer dan eens opgeslagen. De kopieën die je niet houdt, "
 "gaan naar de prullenbak, waar je ze kunt terugzetten."
 
-#: crates/pdfs-gui/src/app/pages/duplicates.rs:111
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:289
+msgid "These photos look alike. They can be copies of one photo or different shots of one moment, so all of them are kept until you untick them. The photos you don't keep move to Trash, where you can restore them."
+msgstr "Deze foto's lijken op elkaar. Het kunnen kopieën van één foto zijn of verschillende opnamen van één moment, dus ze worden allemaal gehouden tot je ze uitvinkt. De foto's die je niet houdt, gaan naar de prullenbak, waar je ze kunt terugzetten."
+
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:323
 #, rust-format
 msgid "{date}, {n} copy"
 msgid_plural "{date}, {n} copies"
 msgstr[0] "{date}, {n} kopie"
 msgstr[1] "{date}, {n} kopieën"
 
-#: crates/pdfs-gui/src/app/pages/duplicates.rs:143
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:330
+#: crates/pdfs-gui/src/app/pages/photos.rs:2994
+#, rust-format
+msgid "{date}, {n} photo"
+msgid_plural "{date}, {n} photos"
+msgstr[0] "{date}, {n} foto"
+msgstr[1] "{date}, {n} foto's"
+
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:364
 #, rust-format
 msgid "Move {n} copy to Trash"
 msgid_plural "Move {n} copies to Trash"
 msgstr[0] "{n} kopie naar prullenbak verplaatsen"
 msgstr[1] "{n} kopieën naar prullenbak verplaatsen"
 
-#: crates/pdfs-gui/src/app/pages/duplicates.rs:235
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:370
+#, rust-format
+msgid "Move {n} photo to Trash"
+msgid_plural "Move {n} photos to Trash"
+msgstr[0] "{n} foto naar prullenbak verplaatsen"
+msgstr[1] "{n} foto's naar prullenbak verplaatsen"
+
+#: crates/pdfs-gui/src/app/pages/duplicates.rs:465
 msgid "Keep"
 msgstr "Houden"
 
@@ -2998,13 +3070,6 @@ msgid_plural "{n} years ago"
 msgstr[0] "{n} jaar geleden"
 msgstr[1] "{n} jaar geleden"
 
-#: crates/pdfs-gui/src/app/pages/photos.rs:2994
-#, rust-format
-msgid "{date}, {n} photo"
-msgid_plural "{date}, {n} photos"
-msgstr[0] "{date}, {n} foto"
-msgstr[1] "{date}, {n} foto's"
-
 #. Translators: a check item in a photo's menu, on while the photo is a favorite.
 #: crates/pdfs-gui/src/app/pages/photos.rs:3231
 msgctxt "state"