fix: Re-apply upstream PRs #1005, #1010, #1003

Re-applies changes that were accidentally discarded during a prior
dry-run cherry-pick reset (git checkout -- .).

- PR #1005: Use HalPowerManager for battery percentage (uint16_t return
  type, remove Battery.h, update theme files)
- PR #1010: Fix dangling pointer in onGoToReader()
- PR #1003: Render image placeholders while waiting for decode (adds
  isCached, renderPlaceholder, renderTextOnly, countUncachedImages,
  renderImagePlaceholders)

Co-authored-by: Cursor <cursoragent@cursor.com>

src/components/themes/lyra/LyraTheme.cpp

@@ -1,6 +1,7 @@
 #include "LyraTheme.h"
 
 #include <GfxRenderer.h>
+#include <HalPowerManager.h>
 #include <HalStorage.h>
 #include <I18n.h>
 #include <Utf8.h>
@@ -10,7 +11,6 @@
 #include <string>
 #include <vector>
 
-#include "Battery.h"
 #include "CrossPointSettings.h"
 #include "RecentBooksStore.h"
 #include "components/UITheme.h"
@@ -88,7 +88,7 @@ const uint8_t* iconForName(UIIcon icon, int size) {
 
 void LyraTheme::drawBatteryLeft(const GfxRenderer& renderer, Rect rect, const bool showPercentage) const {
   // Left aligned: icon on left, percentage on right (reader mode)
-  const uint16_t percentage = battery.readPercentage();
+  const uint16_t percentage = powerManager.getBatteryPercentage();
   const int y = rect.y + 6;
   const int battWidth = LyraMetrics::values.batteryWidth;
 
@@ -125,7 +125,7 @@ void LyraTheme::drawBatteryLeft(const GfxRenderer& renderer, Rect rect, const bo
 
 void LyraTheme::drawBatteryRight(const GfxRenderer& renderer, Rect rect, const bool showPercentage) const {
   // Right aligned: percentage on left, icon on right (UI headers)
-  const uint16_t percentage = battery.readPercentage();
+  const uint16_t percentage = powerManager.getBatteryPercentage();
   const int y = rect.y + 6;
   const int battWidth = LyraMetrics::values.batteryWidth;