Calibre Web Epub Downloading + Calibre Wireless Device Syncing (#219)

Adds support for browsing and downloading books from a Calibre-web
server via OPDS.
How it works
1. Configure server URL in Settings → Calibre Web URL (e.g.,
https://myserver.com:port I use Cloudflare tunnel to make my server
accessible anywhere fwiw)
2. "Calibre Library" will now show on the the home screen
3. Browse the catalog - navigate through categories like "By Newest",
"By Author", "By Series", etc.
4. Download books - select a book and press Confirm to download the EPUB
to your device
Navigation
- Up/Down - Move through entries
- Confirm - Open folder or download book
- Back - Go to parent catalog, or exit to home if at root
- Navigation entries show with > prefix, books show title and author
- Button hints update dynamically ("Open" for folders, "Download" for
books)
Technical details
- Fetches OPDS catalog from {server_url}/opds
- Parses both navigation feeds (catalog links) and acquisition feeds
(downloadable books)
- Maintains navigation history stack for back navigation
- Handles absolute paths in OPDS links correctly (e.g.,
/books/opds/navcatalog/...)
- Downloads EPUBs directly to the SD card root
Note
The server URL should be typed to include https:// if the server
requires it - HTTP→HTTPS redirects may cause SSL errors on ESP32.

* I also changed the home titles to use uppercase for each word and
added a setting to change the size of the side margins

---------

Co-authored-by: Dave Allie <dave@daveallie.com>

src/ScreenComponents.cpp

@@ -2,6 +2,7 @@
 
 #include <GfxRenderer.h>
 
+#include <cstdint>
 #include <string>
 
 #include "Battery.h"
@@ -39,3 +40,26 @@ void ScreenComponents::drawBattery(const GfxRenderer& renderer, const int left,
 
   renderer.fillRect(x + 2, y + 2, filledWidth, batteryHeight - 4);
 }
+
+void ScreenComponents::drawProgressBar(const GfxRenderer& renderer, const int x, const int y, const int width,
+                                       const int height, const size_t current, const size_t total) {
+  if (total == 0) {
+    return;
+  }
+
+  // Use 64-bit arithmetic to avoid overflow for large files
+  const int percent = static_cast<int>((static_cast<uint64_t>(current) * 100) / total);
+
+  // Draw outline
+  renderer.drawRect(x, y, width, height);
+
+  // Draw filled portion
+  const int fillWidth = (width - 4) * percent / 100;
+  if (fillWidth > 0) {
+    renderer.fillRect(x + 2, y + 2, fillWidth, height - 4);
+  }
+
+  // Draw percentage text centered below bar
+  const std::string percentText = std::to_string(percent) + "%";
+  renderer.drawCenteredText(UI_10_FONT_ID, y + height + 15, percentText.c_str());
+}