feat(files): share a folder by link — its page lists what is in it, plays a video above the list

A /watch link may now open one of its owner's own folders (migration 0108: folder_id beside job_id,
exactly one set; a folder's links go with it). The page shows what is in the folder when it is
opened, newest first: a video or a song plays in the same player a file link has, above the list,
each keeping its own resume point; a document only downloads, never opens as a page. A file moved
out stops opening through the link at its next request. Password, expiry and stream-only work as on
a file link; the unfurl names the folder and counts its files, never their names. Source folders
and the Hub cannot be shared.

The folder menu gets "Copy link" and "Share with a link…" (the Share dialog's link half); the rail
marks a folder a live link opens.

Two fixes in the Share dialog on the way: revoking the last link no longer mints a new one at once,
and the new-link form goes back to downloadable after making a link.

frontend/src/i18n/locales/en/downloads.json

@@ -118,7 +118,9 @@
     "newPassword": "New password",
     "savePassword": "Save",
     "removePassword": "Delete",
-    "removePasswordConfirm": "This makes the link public — anyone with the URL can watch it without a password."
+    "removePasswordConfirm": "This makes the link public — anyone with the URL can watch it without a password.",
+    "folderTitle": "Share folder · {{name}}",
+    "folderLinkHint": "Anyone with the link can see the folder — no account needed. They see what is in it when they open it: files you put in later too, not the ones you take out."
   },
   "confirm": {
     "cancelTitle": "Cancel download?",

frontend/src/i18n/locales/en/errors.json

@@ -199,6 +199,7 @@
     "share_own": "That's already your download",
     "share_password_required": "This link needs a password",
     "share_unfinished": "Only a finished download can be shared",
+    "share_folder_kind": "Only a folder of your own can be shared by link",
     "smtp_failed": "The email couldn't be sent — check the SMTP settings",
     "smtp_off": "SMTP isn't configured",
     "spec_not_object": "The profile's settings are malformed",

frontend/src/i18n/locales/en/files.json

@@ -84,7 +84,9 @@
     "deleteBodyEmpty": "The folder is empty. Nothing else changes.",
     "deleteBody_one": "Its file goes back to the folder it came from, and its retention starts again from today.",
     "deleteBody_other": "Its {{count}} files go back to the folders they came from, and their retention starts again from today.",
-    "deleteAction": "Delete folder"
+    "deleteAction": "Delete folder",
+    "shareLink": "Share with a link…",
+    "shared": "Shared with a link"
   },
   "layout": {
     "label": "View",

frontend/src/i18n/locales/hu/downloads.json

@@ -118,7 +118,9 @@
     "newPassword": "Új jelszó",
     "savePassword": "Mentés",
     "removePassword": "Törlés",
-    "removePasswordConfirm": "Ezzel a link publikus lesz — jelszó nélkül bárki megnézheti, akinek megvan az URL."
+    "removePasswordConfirm": "Ezzel a link publikus lesz — jelszó nélkül bárki megnézheti, akinek megvan az URL.",
+    "folderTitle": "Mappa megosztása · {{name}}",
+    "folderLinkHint": "A link birtokában bárki megnézheti a mappát — fiók nélkül is. Azt látja, ami megnyitáskor benne van: a később betett fájlokat is, a kivetteket már nem."
   },
   "confirm": {
     "cancelTitle": "Megszakítod a letöltést?",

frontend/src/i18n/locales/hu/errors.json

@@ -199,6 +199,7 @@
     "share_own": "Ez már a te letöltésed",
     "share_password_required": "Ehhez a linkhez jelszó kell",
     "share_unfinished": "Csak befejezett letöltés osztható meg",
+    "share_folder_kind": "Linkkel csak saját mappa osztható meg",
     "smtp_failed": "Nem sikerült elküldeni a levelet — ellenőrizd az SMTP-beállításokat",
     "smtp_off": "Az SMTP nincs beállítva",
     "spec_not_object": "A profil beállításai hibás formátumúak",

frontend/src/i18n/locales/hu/files.json

@@ -84,7 +84,9 @@
     "deleteBodyEmpty": "A mappa üres. Más nem változik.",
     "deleteBody_one": "A benne lévő fájl visszakerül abba a mappába, ahonnan jött, és a megőrzési ideje mától újraindul.",
     "deleteBody_other": "A benne lévő {{count}} fájl visszakerül abba a mappába, ahonnan jött, és a megőrzési idejük mától újraindul.",
-    "deleteAction": "Mappa törlése"
+    "deleteAction": "Mappa törlése",
+    "shareLink": "Megosztás linkkel…",
+    "shared": "Linkkel megosztva"
   },
   "layout": {
     "label": "Nézet",