port: upstream PR #1342 - Book Info screen, richer metadata, safer controls

Ports upstream PR #1342 (feat: Add Book Info screen, richer metadata,
and safer file-browser controls) with mod-specific adaptations:

- Parse and cache series, seriesIndex, description from EPUB OPF
- Bump book.bin cache version to 6 for new metadata fields
- Add BookInfoActivity (new screen) accessible via Right button in FileBrowser
- Add ManageBook menu via Left button in FileBrowser (replaces upstream hidden delete)
- Guard all delete/archive actions with ConfirmationActivity (10 call sites)
- Add inputArmed gating to ConfirmationActivity to prevent accidental confirmation
- Safe deserialization: readString now returns bool with MAX_STRING_LENGTH guard
- Add series field to RecentBooksStore with JSON and binary serialization
- Add i18n keys: STR_BOOK_INFO, STR_AUTHOR, STR_SERIES, STR_FILE_SIZE, etc.

Made-with: Cursor

lib/I18n/I18nKeys.h

@@ -447,6 +447,13 @@ enum class StrId : uint16_t {
   STR_INDEXING_STATUS_ICON,
   STR_DICTIONARY,
   STR_MANAGE_BOOK,
+  STR_BOOK_INFO,
+  STR_AUTHOR,
+  STR_SERIES,
+  STR_FILE_SIZE,
+  STR_DESCRIPTION,
+  STR_MANAGE,
+  STR_INFO,
   STR_ARCHIVE_BOOK,
   STR_UNARCHIVE_BOOK,
   STR_DELETE_BOOK,