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/2026-02-21_16-30-summary.md

@@ -0,0 +1,24 @@
+# Port Upstream PR #1027: ParsedText Word-Width Cache and Hyphenation Early Exit
+
+## Task
+
+Ported upstream PR #1027 (jpirnay) into the mod. The PR reduces `ParsedText::layoutAndExtractLines` CPU time by 5–9% via two independent optimizations.
+
+## Changes Made
+
+**`lib/Epub/Epub/ParsedText.cpp`** (single file):
+1. Added `#include <cstring>` for `memcpy`/`memcmp`
+2. Added 128-entry direct-mapped word-width cache in the anonymous namespace (`WordWidthCacheEntry`, FNV-1a hash, `cachedMeasureWordWidth`). 4 KB in BSS, zero heap allocation.
+3. Switched `calculateWordWidths` to use `cachedMeasureWordWidth` instead of `measureWordWidth`
+4. Added `lineBreakIndices.reserve(totalWordCount / 8 + 1)` in `computeLineBreaks`
+5. In `hyphenateWordAtIndex`: added reusable `prefix` string buffer (avoids per-iteration `substr` allocations) and early exit `break` when prefix exceeds available width (ascending byte-offset order means all subsequent candidates will also be too wide)
+
+**`mod/prs/MERGED.md`**: Added PR #1027 entry (TOC link + full section with context, changes, differences, discussion).
+
+## Key Adaptation
+
+The upstream PR targets `std::list`-based code, but our mod already uses `std::vector` (from PR #1038). List-specific optimizations (splice in `extractLine`, `std::next` vs `std::advance`, `continuesVec` pointer sync) were not applicable. Only the algorithmic improvements were ported.
+
+## Follow-up Items
+
+- None. Port is complete.