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/DictionaryDefinitionActivity.h

@@ -0,0 +1,64 @@
+#pragma once
+#include <EpdFontFamily.h>
+
+#include <string>
+#include <vector>
+
+#include "activities/Activity.h"
+
+class DictionaryDefinitionActivity final : public Activity {
+ public:
+  explicit DictionaryDefinitionActivity(GfxRenderer& renderer, MappedInputManager& mappedInput,
+                                        const std::string& headword, const std::string& definition, int readerFontId,
+                                        uint8_t orientation, bool hasDoneButton = false)
+      : Activity("DictionaryDefinition", renderer, mappedInput),
+        headword(headword),
+        definition(definition),
+        readerFontId(readerFontId),
+        orientation(orientation),
+        hasDoneButton(hasDoneButton) {}
+
+  void onEnter() override;
+  void onExit() override;
+  void loop() override;
+  void render(RenderLock&&) override;
+
+ private:
+  // A positioned text segment within a wrapped line (pre-calculated x offset and style).
+  struct Segment {
+    std::string text;
+    int16_t x;
+    EpdFontFamily::Style style;
+  };
+
+  // An intermediate token produced by the HTML parser before word-wrapping.
+  struct TextAtom {
+    std::string text;
+    EpdFontFamily::Style style;
+    bool isNewline;
+    int indent;  // pixels to indent the new line (for nested lists)
+  };
+
+  // Tracks ordered/unordered list nesting during HTML parsing.
+  struct ListState {
+    int counter;   // incremented per <li>, 0 = not yet used
+    bool isAlpha;  // true for list-style-type: lower-alpha
+  };
+
+  std::string headword;
+  std::string definition;
+  int readerFontId;
+  uint8_t orientation;
+  bool hasDoneButton;  // If true, Confirm shows "Done" and finishes with !isCancelled (exit to reader)
+
+  std::vector<std::vector<Segment>> wrappedLines;
+  int currentPage = 0;
+  int linesPerPage = 0;
+  int totalPages = 0;
+  bool firstRender = true;
+
+  std::vector<TextAtom> parseHtml(const std::string& html);
+  static std::string decodeEntity(const std::string& entity);
+  static bool isRenderableCodepoint(uint32_t cp);
+  void wrapText();
+};