refactor: Eliminated relative path includes (#1961)

## Summary

Relative includes can hide inappropriate dependency relationships. In
this case, I found that lib/KOReaderSync/KOReaderCredentialStore.cpp was
dependent on src/JsonSettingsIO.h -- a lib -> app dependency, the
opposite direction dependencies should flow in this project.

This change replaces all relative includes with root-relative includes,
and corrects the KOReaderCredentialStore dependency by moving its JSON
settings serialization local to the KOReaderSync library.

---

### AI Usage

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please be transparent about their usage as it
helps set the right context for reviewers.

Did you use AI tools to help write this code? _**PARTIALLY**_

src/activities/boot_sleep/BootActivity.h

@@ -1,5 +1,5 @@
 #pragma once
-#include "../Activity.h"
+#include "activities/Activity.h"
 
 class BootActivity final : public Activity {
  public:

src/activities/boot_sleep/SleepActivity.h

@@ -1,5 +1,5 @@
 #pragma once
-#include "../Activity.h"
+#include "activities/Activity.h"
 
 class Bitmap;
 

src/activities/browser/OpdsBookBrowserActivity.h

@@ -5,8 +5,8 @@
 #include <utility>
 #include <vector>
 
-#include "../Activity.h"
 #include "OpdsServerStore.h"
+#include "activities/Activity.h"
 #include "util/ButtonNavigator.h"
 
 /**

src/activities/home/CrashActivity.h

@@ -1,5 +1,5 @@
 #pragma once
-#include "../Activity.h"
+#include "activities/Activity.h"
 
 class CrashActivity final : public Activity {
   std::string panicMessage;

src/activities/home/FileBrowserActivity.cpp

@@ -8,9 +8,9 @@
 
 #include <algorithm>
 
-#include "../util/ConfirmationActivity.h"
 #include "CrossPointSettings.h"
 #include "MappedInputManager.h"
+#include "activities/util/ConfirmationActivity.h"
 #include "components/UITheme.h"
 #include "fontIds.h"
 

src/activities/home/FileBrowserActivity.h

@@ -4,8 +4,8 @@
 #include <string>
 #include <vector>
 
-#include "../Activity.h"
 #include "RecentBooksStore.h"
+#include "activities/Activity.h"
 #include "util/ButtonNavigator.h"
 
 class FileBrowserActivity final : public Activity {

src/activities/home/HomeActivity.h

@@ -2,8 +2,8 @@
 #include <functional>
 #include <vector>
 
-#include "../Activity.h"
 #include "./FileBrowserActivity.h"
+#include "activities/Activity.h"
 #include "util/ButtonNavigator.h"
 
 struct RecentBook;

src/activities/home/RecentBooksActivity.h

@@ -5,8 +5,8 @@
 #include <string>
 #include <vector>
 
-#include "../Activity.h"
 #include "RecentBooksStore.h"
+#include "activities/Activity.h"
 #include "util/ButtonNavigator.h"
 
 class RecentBooksActivity final : public Activity {

src/activities/network/NetworkModeSelectionActivity.h

@@ -2,7 +2,7 @@
 
 #include <functional>
 
-#include "../Activity.h"
+#include "activities/Activity.h"
 #include "util/ButtonNavigator.h"
 
 enum class NetworkMode { JOIN_NETWORK, CONNECT_CALIBRE, CREATE_HOTSPOT };

src/activities/reader/EpubReaderChapterSelectionActivity.h

@@ -3,7 +3,7 @@
 
 #include <memory>
 
-#include "../Activity.h"
+#include "activities/Activity.h"
 #include "util/ButtonNavigator.h"
 
 class EpubReaderChapterSelectionActivity final : public Activity {

src/activities/reader/EpubReaderFootnotesActivity.h

@@ -6,7 +6,7 @@
 #include <functional>
 #include <vector>
 
-#include "../Activity.h"
+#include "activities/Activity.h"
 #include "util/ButtonNavigator.h"
 
 class EpubReaderFootnotesActivity final : public Activity {

src/activities/reader/EpubReaderMenuActivity.h

@@ -5,7 +5,7 @@
 #include <string>
 #include <vector>
 
-#include "../Activity.h"
+#include "activities/Activity.h"
 #include "util/ButtonNavigator.h"
 
 class EpubReaderMenuActivity final : public Activity {

src/activities/reader/ReaderActivity.h

@@ -1,7 +1,7 @@
 #pragma once
 #include <memory>
 
-#include "../Activity.h"
+#include "activities/Activity.h"
 #include "activities/home/FileBrowserActivity.h"
 
 class Epub;

src/activities/reader/XtcReaderChapterSelectionActivity.h

@@ -3,7 +3,7 @@
 
 #include <memory>
 
-#include "../Activity.h"
+#include "activities/Activity.h"
 #include "util/ButtonNavigator.h"
 
 class XtcReaderChapterSelectionActivity final : public Activity {

src/activities/settings/LanguageSelectActivity.h

@@ -5,7 +5,7 @@
 
 #include <functional>
 
-#include "../Activity.h"
+#include "activities/Activity.h"
 #include "components/UITheme.h"
 #include "util/ButtonNavigator.h"
 

src/activities/util/BmpViewerActivity.h

@@ -3,8 +3,8 @@
 #include <functional>
 #include <string>
 
-#include "../Activity.h"
 #include "MappedInputManager.h"
+#include "activities/Activity.h"
 
 class BmpViewerActivity final : public Activity {
  public:

src/activities/util/ConfirmationActivity.cpp

@@ -2,8 +2,8 @@
 
 #include <I18n.h>
 
-#include "../../components/UITheme.h"
 #include "HalDisplay.h"
+#include "components/UITheme.h"
 
 ConfirmationActivity::ConfirmationActivity(GfxRenderer& renderer, MappedInputManager& mappedInput,
                                            const std::string& heading, const std::string& body)

src/activities/util/ConfirmationActivity.h

@@ -2,8 +2,8 @@
 #include <functional>
 #include <string>
 
-#include "../../fontIds.h"
-#include "../Activity.h"
+#include "activities/Activity.h"
+#include "fontIds.h"
 
 class ConfirmationActivity : public Activity {
  private:

src/activities/util/FullScreenMessageActivity.h

@@ -5,7 +5,7 @@
 #include <string>
 #include <utility>
 
-#include "../Activity.h"
+#include "activities/Activity.h"
 
 class FullScreenMessageActivity final : public Activity {
   std::string text;

src/activities/util/KeyboardEntryActivity.h

@@ -6,7 +6,7 @@
 #include <string>
 #include <utility>
 
-#include "../Activity.h"
+#include "activities/Activity.h"
 #include "util/ButtonNavigator.h"
 
 struct KeyDef {