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

## Summary

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.

## Additional Context

* 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/activities/settings/SettingsActivity.cpp

@@ -3,6 +3,9 @@
 #include <GfxRenderer.h>
 #include <HardwareSerial.h>
 
+#include <cstring>
+
+#include "CalibreSettingsActivity.h"
 #include "CrossPointSettings.h"
 #include "MappedInputManager.h"
 #include "OtaUpdateActivity.h"
@@ -10,7 +13,7 @@
 
 // Define the static settings list
 namespace {
-constexpr int settingsCount = 16;
+constexpr int settingsCount = 17;
 const SettingInfo settingsList[settingsCount] = {
     // Should match with SLEEP_SCREEN_MODE
     SettingInfo::Enum("Sleep Screen", &CrossPointSettings::sleepScreen, {"Dark", "Light", "Custom", "Cover", "None"}),
@@ -35,6 +38,7 @@ const SettingInfo settingsList[settingsCount] = {
                       {"1 min", "5 min", "10 min", "15 min", "30 min"}),
     SettingInfo::Enum("Refresh Frequency", &CrossPointSettings::refreshFrequency,
                       {"1 page", "5 pages", "10 pages", "15 pages", "30 pages"}),
+    SettingInfo::Action("Calibre Settings"),
     SettingInfo::Action("Check for updates")};
 }  // namespace
 
@@ -132,7 +136,15 @@ void SettingsActivity::toggleCurrentSetting() {
       SETTINGS.*(setting.valuePtr) = currentValue + setting.valueRange.step;
     }
   } else if (setting.type == SettingType::ACTION) {
-    if (std::string(setting.name) == "Check for updates") {
+    if (strcmp(setting.name, "Calibre Settings") == 0) {
+      xSemaphoreTake(renderingMutex, portMAX_DELAY);
+      exitActivity();
+      enterNewActivity(new CalibreSettingsActivity(renderer, mappedInput, [this] {
+        exitActivity();
+        updateRequired = true;
+      }));
+      xSemaphoreGive(renderingMutex);
+    } else if (strcmp(setting.name, "Check for updates") == 0) {
       xSemaphoreTake(renderingMutex, portMAX_DELAY);
       exitActivity();
       enterNewActivity(new OtaUpdateActivity(renderer, mappedInput, [this] {