feat(dashboard): playtime chart, recently played and a playing hint

The dashboard shows the playtime of the last 30 days and Steam's recently
played games. The detail page offers to set a backlog game to Playing when
Steam reports recent playtime; unsaved edits in the backlog card stay.

public/i18n/en.json

@@ -98,7 +98,11 @@
     "OTHER_SUGGESTION": "Other pick",
     "BACKLOG_EMPTY": "Your backlog is empty. Nice!",
     "SUMMARY_FAILED": "Could not load the overview.",
-    "RETRY": "Try again"
+    "RETRY": "Try again",
+    "ACTIVITY": "Playtime",
+    "ACTIVITY_TOTAL": "{{time}} in {{days}} days",
+    "ACTIVITY_EMPTY": "No playtime recorded yet. Every sync from now on counts.",
+    "RECENTLY_PLAYED": "Recently played (2 weeks)"
   },
   "LIBRARY": {
     "TITLE": "Game Library",
@@ -141,7 +145,9 @@
     "REMAINING": "Remaining",
     "COMPLETION": "Completion",
     "NO_ACHIEVEMENTS": "This game has no achievements on Steam.",
-    "STATS_HIDDEN": "Stats hidden by Steam — set your profile and game details to public to see achievements."
+    "STATS_HIDDEN": "Stats hidden by Steam — set your profile and game details to public to see achievements.",
+    "PLAYED_RECENTLY": "Steam says you played this game for {{time}} in the last 2 weeks, but it is still in your backlog.",
+    "SET_PLAYING": "Set to \"Playing\""
   },
   "LANDING": {
     "STATS_TITLE": "Community stats",