fix(sync): report interactive push/pull failures when offline

An interactive pull could exit without any feedback while push showed
'Failed to push progress', from two silent exits on the pull path:

- pulling an unlinked book delegated to a non-interactive push whose
  failure produced no UI (and could be swallowed by the 25s debounce)
- when the device is connected at the IP level but has no internet,
  NetworkMgr:willRerunWhenOnline drops the callback with neither a
  rerun nor any UI (it only guarantees isConnected)

Now the connected-but-offline state is detected up front and reported
('No internet connection. Progress was not pulled/pushed.'), resolve
failures notify interactively, pulling with progress sync disabled
explains itself instead of silently returning, and the generic pull
failure message mentions the network connection like push does.

main.lua

@@ -990,7 +990,15 @@ function Bookhoard:updateProgress(ensure_networking, interactive)
         return
     end
 
-    if not self.settings.sync_progress then return end
+    if not self.settings.sync_progress then
+        if interactive then
+            UIManager:show(InfoMessage:new{
+                text = _("Reading progress sync is disabled (see What to sync)."),
+                timeout = 3,
+            })
+        end
+        return
+    end
 
     if not self.ui.document then
         if interactive then
@@ -1007,10 +1015,20 @@ function Bookhoard:updateProgress(ensure_networking, interactive)
         return
     end
 
-    if ensure_networking
-        and NetworkMgr:willRerunWhenOnline(function() self:updateProgress(ensure_networking, interactive) end) then
+    if ensure_networking then
+        -- Same silent-drop case as getProgress: connected but no internet
+        -- means willRerunWhenOnline neither reruns nor shows any UI.
+        if interactive and NetworkMgr:isConnected() and not NetworkMgr:isOnline() then
+            UIManager:show(InfoMessage:new{
+                text = _("No internet connection. Progress was not pushed."),
+                timeout = 3,
+            })
             return
         end
+        if NetworkMgr:willRerunWhenOnline(function() self:updateProgress(ensure_networking, interactive) end) then
+            return
+        end
+    end
 
     UIManager:scheduleIn(0.5, function()
         self:_doUpdateProgress(interactive)
@@ -1078,30 +1096,53 @@ function Bookhoard:getProgress(ensure_networking, interactive)
         return
     end
 
-    if not self.settings.sync_progress then return end
+    if not self.settings.sync_progress then
+        if interactive then
+            UIManager:show(InfoMessage:new{
+                text = _("Reading progress sync is disabled (see What to sync)."),
+                timeout = 3,
+            })
+        end
+        return
+    end
 
     local now = UIManager:getElapsedTimeSinceBoot()
     if not interactive and now - self.pull_timestamp <= API_CALL_DEBOUNCE_DELAY then
         return
     end
 
-    if ensure_networking
-        and NetworkMgr:willRerunWhenOnline(function() self:getProgress(ensure_networking, interactive) end) then
+    if ensure_networking then
+        -- willRerunWhenOnline silently drops the action (no rerun, no UI)
+        -- when the device is connected at the IP level but has no internet
+        -- access: it only guarantees isConnected, and in that state the
+        -- framework re-connects without ever invoking the callback. Catch
+        -- that state up front so an interactive pull never no-ops silently.
+        if interactive and NetworkMgr:isConnected() and not NetworkMgr:isOnline() then
+            UIManager:show(InfoMessage:new{
+                text = _("No internet connection. Progress was not pulled."),
+                timeout = 3,
+            })
             return
         end
+        if NetworkMgr:willRerunWhenOnline(function() self:getProgress(ensure_networking, interactive) end) then
+            return
+        end
+    end
 
     local book_uuid = self:getBookhoardUUID()
     if not book_uuid then
-        -- No cached UUID yet (first open of a freshly downloaded book). Bootstrap
-        -- it by pushing once: the server resolves the book by SHA-256 and returns
-        -- the UUID, which the push handler caches. Then retry the pull.
+        -- No cached UUID yet (first open of a freshly downloaded book). Link
+        -- the book with a read-only SHA-256 lookup, then pull. Progress is
+        -- never pushed here: the device sits on the first page of a book the
+        -- server may hold mid-read, and pushing that would overwrite/server-
+        -- conflict the real progress before the pull could deliver it.
         if interactive then
             UIManager:show(InfoMessage:new{
                 text = _("Linking this book to Bookhoard first…"),
                 timeout = 3,
             })
         end
-        self:_bootstrapUUIDThenPull(interactive)
+        self:_linkBookThenPull(interactive)
         return
     end
 
@@ -1201,7 +1242,7 @@ function Bookhoard:_doGetProgress(interactive)
         if not ok or not result then
             if interactive then
                 UIManager:show(InfoMessage:new{
-                    text = _("Failed to pull progress."),
+                    text = _("Failed to pull progress. Check your network connection."),
                     timeout = 3,
                 })
             end