mod: Phase 1 - bring forward mod-exclusive files with ActivityManager migration

Brings ~55 mod-exclusive files to the upstream-based mod/master-resync branch:

Activities (migrated to new ActivityManager pattern):
- Clock/Time: SetTimeActivity, SetTimezoneOffsetActivity, NtpSyncActivity
- Dictionary: DictionaryDefinitionActivity, DictionarySuggestionsActivity,
  DictionaryWordSelectActivity, LookedUpWordsActivity
- Bookmark: EpubReaderBookmarkSelectionActivity
- Book management: BookManageMenuActivity, EndOfBookMenuActivity
- OPDS: OpdsServerListActivity, OpdsSettingsActivity
- Utility: DirectoryPickerActivity, NumericStepperActivity

Utilities (unchanged):
- BookManager, BookSettings, BookmarkStore, BootNtpSync
- Dictionary, LookupHistory, TimeSync, OpdsServerStore

Libraries: PlaceholderCover, TableData, ChapterXPathIndexer
Scripts: inject_mod_version, generate_book_icon, preview_placeholder_cover
Docs: KOReader sync XPath mapping

Migration changes:
- ActivityWithSubactivity -> Activity base class
- Callback constructors -> finish()/setResult() pattern
- enterNewActivity() -> startActivityForResult()
- Activity::RenderLock&& -> RenderLock&&

These files won't compile yet - they reference mod settings and I18n
strings that will be added in subsequent phases.

Made-with: Cursor

chat-summaries/2026-02-19_21-30-summary.md

@@ -0,0 +1,33 @@
+# Port Upstream PRs #997, #1003, #1005, #1010
+
+## Task
+Cherry-pick / port four upstream PRs from crosspoint-reader/crosspoint-reader into the mod fork.
+
+## Changes Made
+
+### PR #997 -- Already Ported (no changes)
+Glyph null-safety in `getSpaceWidth`/`getTextAdvanceX` was already present via commit `c1b8e53`.
+
+### PR #1010 -- Fix Dangling Pointer
+- **src/main.cpp**: `onGoToReader()` now copies the `initialEpubPath` string before calling `exitActivity()`, preventing a dangling reference when the owning activity is destroyed.
+
+### PR #1005 -- Use HalPowerManager for Battery Percentage
+- **lib/hal/HalPowerManager.h**: Changed `getBatteryPercentage()` return type from `int` to `uint16_t`.
+- **lib/hal/HalPowerManager.cpp**: Same return type change.
+- **src/Battery.h**: Emptied contents (was `static BatteryMonitor battery(BAT_GPIO0)`).
+- **src/main.cpp**: Removed `#include "Battery.h"`.
+- **src/activities/home/HomeActivity.cpp**: Removed `#include "Battery.h"`.
+- **src/components/themes/BaseTheme.cpp**: Replaced `Battery.h` include with `HalPowerManager.h`, replaced `battery.readPercentage()` with `powerManager.getBatteryPercentage()` (2 occurrences).
+- **src/components/themes/lyra/LyraTheme.cpp**: Same replacements (2 occurrences).
+
+### PR #1003 -- Render Image Placeholders While Waiting for Decode
+- **lib/Epub/Epub/blocks/ImageBlock.h/.cpp**: Added `isCached()` method that checks if the `.pxc` cache file exists.
+- **lib/Epub/Epub/Page.h/.cpp**: Added `PageImage::isCached()`, `PageImage::renderPlaceholder()`, `Page::renderTextOnly()`, `Page::countUncachedImages()`, `Page::renderImagePlaceholders()`. Added `#include <GfxRenderer.h>` to Page.h.
+- **src/activities/reader/EpubReaderActivity.cpp**: Modified `renderContents()` to check for uncached images and display text + placeholder rectangles immediately (Phase 1 with HALF_REFRESH), then proceed with full image decode and display (Phase 2 with fast refresh). Existing mod-specific double FAST_REFRESH logic for anti-aliased image pages is preserved for the cached-image path.
+
+## Build Result
+SUCCESS -- RAM: 31.5%, Flash: 70.4%. No linter errors.
+
+## Follow-up Items
+- PR #1003 is still open upstream (not merged); may need to rebase if upstream changes before merge.
+- The phased rendering for uncached images skips the mod's double FAST_REFRESH technique (relies on Phase 1's HALF_REFRESH instead). If grayscale quality on first-decode image pages is suboptimal, this could be revisited.