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/2026-03-02_00-00-summary.md

@@ -0,0 +1,33 @@
+# OPDS Post-Download Prompt Screen
+
+## Task
+After an OPDS download completes, instead of immediately returning to the catalog listing, show a prompt screen with two options: "Back to Listing" and "Open Book". A 5-second auto-timer executes the default action. A per-server setting controls which option is default (back to listing by default for backward compatibility).
+
+## Changes Made
+
+### New i18n strings
+- `lib/I18n/translations/english.yaml` — Added `STR_DOWNLOAD_COMPLETE`, `STR_OPEN_BOOK`, `STR_BACK_TO_LISTING`, `STR_AFTER_DOWNLOAD`
+- Regenerated `lib/I18n/I18nKeys.h`, `lib/I18n/I18nStrings.cpp` via `gen_i18n.py`
+
+### Per-server setting
+- `src/OpdsServerStore.h` — Added `afterDownloadAction` field to `OpdsServer` (0 = back to listing, 1 = open book)
+- `src/OpdsServerStore.cpp` — Serialized/deserialized `after_download` in JSON
+
+### Browser activity
+- `src/activities/browser/OpdsBookBrowserActivity.h` — Added `DOWNLOAD_COMPLETE` state, `onGoToReader` callback, `downloadedFilePath`, `downloadCompleteTime`, `promptSelection` members, `executePromptAction()` method
+- `src/activities/browser/OpdsBookBrowserActivity.cpp` — On download success: transition to `DOWNLOAD_COMPLETE` state instead of `BROWSING`. Added loop handling (Left/Right to toggle selection, Confirm to execute, Back to go to listing, 5s auto-timer). Added render for prompt screen with bracketed selection UI. Added `executePromptAction()` helper.
+
+### Callback threading
+- `src/main.cpp` — Passed `onGoToReader` callback to `OpdsBookBrowserActivity` constructor in both single-server and multi-server code paths
+
+### Settings UI
+- `src/activities/settings/OpdsSettingsActivity.cpp` — Incremented `BASE_ITEMS` from 6 to 7. Added "After Download" field at index 6 (toggles between "Back to Listing" and "Open Book"). Shifted Delete to index 7.
+
+### Countdown refinements (follow-up)
+- Added live countdown display using `FAST_REFRESH` -- shows "(5s)", "(4s)", etc., updating each second
+- Any button press (Left/Right to change selection, Back, Confirm) cancels the countdown entirely instead of resetting it
+- Added `countdownActive` bool and `lastCountdownSecond` int to track state without redundant redraws
+
+## Follow-up Items
+- Translations for the 4 new strings in non-English languages
+- On-device testing of the full flow (download → prompt → open book / back to listing)