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

src/activities/reader/DictionaryWordSelectActivity.h

@@ -0,0 +1,67 @@
+#pragma once
+#include <Epub/Page.h>
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "activities/Activity.h"
+
+class DictionaryWordSelectActivity final : public Activity {
+ public:
+  explicit DictionaryWordSelectActivity(GfxRenderer& renderer, MappedInputManager& mappedInput,
+                                        std::unique_ptr<Page> page, int fontId, int marginLeft, int marginTop,
+                                        const std::string& cachePath, uint8_t orientation,
+                                        const std::string& nextPageFirstWord = "")
+      : Activity("DictionaryWordSelect", renderer, mappedInput),
+        page(std::move(page)),
+        fontId(fontId),
+        marginLeft(marginLeft),
+        marginTop(marginTop),
+        cachePath(cachePath),
+        orientation(orientation),
+        nextPageFirstWord(nextPageFirstWord) {}
+
+  void onEnter() override;
+  void onExit() override;
+  void loop() override;
+  void render(RenderLock&&) override;
+
+ private:
+  struct WordInfo {
+    std::string text;
+    std::string lookupText;
+    int16_t screenX;
+    int16_t screenY;
+    int16_t width;
+    int16_t row;
+    int continuationIndex;
+    int continuationOf;
+    WordInfo(const std::string& t, int16_t x, int16_t y, int16_t w, int16_t r)
+        : text(t), lookupText(t), screenX(x), screenY(y), width(w), row(r), continuationIndex(-1), continuationOf(-1) {}
+  };
+
+  struct Row {
+    int16_t yPos;
+    std::vector<int> wordIndices;
+  };
+
+  std::unique_ptr<Page> page;
+  int fontId;
+  int marginLeft;
+  int marginTop;
+  std::string cachePath;
+  uint8_t orientation;
+  std::string nextPageFirstWord;
+
+  std::vector<WordInfo> words;
+  std::vector<Row> rows;
+  int currentRow = 0;
+  int currentWordInRow = 0;
+
+  bool isLandscape() const;
+  bool isInverted() const;
+  void extractWords();
+  void mergeHyphenatedWords();
+  void drawHints();
+};