fix(cli,core,fuse,gui): say why the mount keeps failing, and back off

A mount that failed on every try retried every 5 s forever, and the
reason was only in the journal: the app and the tray said Connecting...
for days (B263, issue #40). The retry now doubles to a 2-minute ceiling,
and the last failure is kept in mount-failure.json for the app, the
tray, pdfs diagnose and systemctl status.

The early returns in mount left the workers they had started running
beside the next attempt (B264). They are now stopped on every error
path, without telling systemd the daemon is stopping.

po/fr.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: 2026-10-26 22:26+0100\n"
+"POT-Creation-Date: 2026-10-31 10:37+0100\n"
 "PO-Revision-Date: 2026-09-23 12:00+0200\n"
 "Last-Translator: Proton Drive for Linux contributors\n"
 "Language-Team: French\n"
@@ -424,14 +424,25 @@ msgstr "Non connecté"
 msgid "The Proton Drive service isn't running."
 msgstr "Le service Proton Drive n’est pas en cours d’exécution."
 
-#: crates/pdfs-gui/src/app/main.rs:1803
+#: crates/pdfs-gui/src/app/main.rs:1813
+msgid "Can't open your Drive"
+msgstr "Impossible d’ouvrir Proton Drive"
+
+#: crates/pdfs-gui/src/app/main.rs:1816
+#, rust-format
+msgid ""
+"The Proton Drive service keeps failing to start and tries again on its own. "
+"The last error was: {error}"
+msgstr "Le service Proton Drive n’arrive pas à démarrer et réessaie de lui-même. Dernière erreur : {error}"
+
+#: crates/pdfs-gui/src/app/main.rs:1824
 #: crates/pdfs-gui/src/app/pages/status.rs:355
 #: crates/pdfs-gui/src/hud/mod.rs:269 crates/pdfs-gui/src/hud/mod.rs:579
-#: crates/pdfs-gui/src/main.rs:475 crates/pdfs-gui/src/main.rs:517
+#: crates/pdfs-gui/src/main.rs:493 crates/pdfs-gui/src/main.rs:535
 msgid "Connecting…"
 msgstr "Connexion…"
 
-#: crates/pdfs-gui/src/app/main.rs:1804
+#: crates/pdfs-gui/src/app/main.rs:1825
 msgid "Waiting for the Proton Drive service to start."
 msgstr "En attente du démarrage du service Proton Drive."
 
@@ -2908,7 +2919,7 @@ msgid "Sync paused until you resume"
 msgstr "Synchronisation en pause jusqu’à la reprise"
 
 #: crates/pdfs-gui/src/app/pages/locations.rs:570
-#: crates/pdfs-gui/src/app/pages/status.rs:1445 crates/pdfs-gui/src/main.rs:290
+#: crates/pdfs-gui/src/app/pages/status.rs:1445 crates/pdfs-gui/src/main.rs:308
 msgid "Sync paused"
 msgstr "Synchronisation en pause"
 
@@ -5138,7 +5149,7 @@ msgstr "Reprise {time}"
 msgid "Until you resume"
 msgstr "Jusqu’à la reprise"
 
-#: crates/pdfs-gui/src/app/pages/status.rs:1464 crates/pdfs-gui/src/main.rs:292
+#: crates/pdfs-gui/src/app/pages/status.rs:1464 crates/pdfs-gui/src/main.rs:310
 #, rust-format
 msgid "{n} change needs attention"
 msgid_plural "{n} changes need attention"
@@ -6375,52 +6386,57 @@ msgstr "Proton Drive ne répond pas"
 msgid "Signed in as {username} — locked"
 msgstr "Connecté en tant que {username} — verrouillé"
 
-#: crates/pdfs-gui/src/main.rs:200
+#: crates/pdfs-gui/src/main.rs:209
+#, rust-format
+msgid "Signed in as {username} — can't open your Drive"
+msgstr "Connecté en tant que {username} — impossible d’ouvrir Proton Drive"
+
+#: crates/pdfs-gui/src/main.rs:218
 #, rust-format
 msgid "Signed in as {username} — not connected"
 msgstr "Connecté en tant que {username} — non connecté"
 
-#: crates/pdfs-gui/src/main.rs:205
+#: crates/pdfs-gui/src/main.rs:223
 msgid "Not signed in"
 msgstr "Non connecté"
 
 #. Translators: {error} is an error message, in English.
-#: crates/pdfs-gui/src/main.rs:208
+#: crates/pdfs-gui/src/main.rs:226
 #, rust-format
 msgid "Error: {error}"
 msgstr "Erreur : {error}"
 
-#: crates/pdfs-gui/src/main.rs:230
+#: crates/pdfs-gui/src/main.rs:248
 msgid "Proton Drive sent an unexpected reply"
 msgstr "Proton Drive a envoyé une réponse inattendue"
 
-#: crates/pdfs-gui/src/main.rs:284
+#: crates/pdfs-gui/src/main.rs:302
 msgid "Session expired — sign in again"
 msgstr "Session expirée — reconnectez-vous"
 
-#: crates/pdfs-gui/src/main.rs:286
+#: crates/pdfs-gui/src/main.rs:304
 msgid "Sign-in not saved — unlock your keyring"
 msgstr "Connexion non enregistrée — déverrouillez votre trousseau"
 
-#: crates/pdfs-gui/src/main.rs:289
+#: crates/pdfs-gui/src/main.rs:307
 msgid "Update not finished — restart Proton Drive"
 msgstr "Mise à jour inachevée — redémarrez Proton Drive"
 
-#: crates/pdfs-gui/src/main.rs:299
+#: crates/pdfs-gui/src/main.rs:317
 #, rust-format
 msgid "Up to date in {mountpoint} ({n} pinned)"
 msgid_plural "Up to date in {mountpoint} ({n} pinned)"
 msgstr[0] "À jour dans {mountpoint} ({n} épinglé)"
 msgstr[1] "À jour dans {mountpoint} ({n} épinglés)"
 
-#: crates/pdfs-gui/src/main.rs:306
+#: crates/pdfs-gui/src/main.rs:324
 #, rust-format
 msgid "Syncing — {queued} ({n} pinned)"
 msgid_plural "Syncing — {queued} ({n} pinned)"
 msgstr[0] "Synchronisation — {queued} ({n} épinglé)"
 msgstr[1] "Synchronisation — {queued} ({n} épinglés)"
 
-#: crates/pdfs-gui/src/main.rs:313
+#: crates/pdfs-gui/src/main.rs:331
 #, rust-format
 msgid "Offline — cached files only ({n} pinned)"
 msgid_plural "Offline — cached files only ({n} pinned)"
@@ -6428,60 +6444,60 @@ msgstr[0] "Hors ligne — fichiers en cache uniquement ({n} épinglé)"
 msgstr[1] "Hors ligne — fichiers en cache uniquement ({n} épinglés)"
 
 #. Translators: {queued} is a queue summary such as "3 uploads queued".
-#: crates/pdfs-gui/src/main.rs:319
+#: crates/pdfs-gui/src/main.rs:337
 #, rust-format
 msgid "Offline — {queued}"
 msgstr "Hors ligne — {queued}"
 
 #. Translators: a menu item that opens the list of failing changes.
-#: crates/pdfs-gui/src/main.rs:358
+#: crates/pdfs-gui/src/main.rs:376
 #, rust-format
 msgid "{n} issue — View"
 msgid_plural "{n} issues — View"
 msgstr[0] "{n} problème — Afficher"
 msgstr[1] "{n} problèmes — Afficher"
 
-#: crates/pdfs-gui/src/main.rs:465
+#: crates/pdfs-gui/src/main.rs:483
 msgid "Sign In…"
 msgstr "Se connecter…"
 
-#: crates/pdfs-gui/src/main.rs:466
+#: crates/pdfs-gui/src/main.rs:484
 msgid "Sign In Again…"
 msgstr "Se reconnecter…"
 
-#: crates/pdfs-gui/src/main.rs:469
+#: crates/pdfs-gui/src/main.rs:487
 msgid "Open Proton Drive"
 msgstr "Ouvrir Proton Drive"
 
-#: crates/pdfs-gui/src/main.rs:473
+#: crates/pdfs-gui/src/main.rs:491
 msgid "Restart Proton Drive"
 msgstr "Redémarrer Proton Drive"
 
-#: crates/pdfs-gui/src/main.rs:482
+#: crates/pdfs-gui/src/main.rs:500
 msgid "Open Folder"
 msgstr "Ouvrir le dossier"
 
-#: crates/pdfs-gui/src/main.rs:494
+#: crates/pdfs-gui/src/main.rs:512
 msgid "Resume Sync"
 msgstr "Reprendre la synchronisation"
 
-#: crates/pdfs-gui/src/main.rs:496
+#: crates/pdfs-gui/src/main.rs:514
 msgid "Pause Sync"
 msgstr "Mettre en pause la synchronisation"
 
-#: crates/pdfs-gui/src/main.rs:515
+#: crates/pdfs-gui/src/main.rs:533
 msgid "Connect"
 msgstr "Connecter"
 
-#: crates/pdfs-gui/src/main.rs:522
+#: crates/pdfs-gui/src/main.rs:540
 msgid "Hide Tray Icon"
 msgstr "Masquer l’icône de la zone de notification"
 
-#: crates/pdfs-gui/src/main.rs:526
+#: crates/pdfs-gui/src/main.rs:544
 msgid "Stop Proton Drive…"
 msgstr "Arrêter Proton Drive…"
 
-#: crates/pdfs-gui/src/main.rs:530
+#: crates/pdfs-gui/src/main.rs:548
 msgid "Quit"
 msgstr "Quitter"