Elements dialog (F7): add Tables and Lists views

[dan1982code]

Elements dialog (F7): add Tables and Lists views

Follow-up to the Pages-view work (#775). The Elements dialog's View dropdown now offers
Headings / Links / Pages / Tables / Lists. The two new views each show one row per
Table / List marker in the document — the same containers that Go → Next/Previous Table and
Next/Previous List already jump between.

Behavior

• A Tables row shows the table's caption — the text the table's first row reads, as next/previous
  Table navigation announces it (or, for a table with no caption, the line it sits on).
• A Lists row shows the list's first rendered item — exactly what next/previous List navigation
  announces (List markers carry no text of their own).
• No numbering: rows read like the Links view and like container navigation, so what you pick in
  the list and what you hear when you land match.
• Choosing a row (double-click or OK on the selection) jumps to the container and announces the
  landing line, like the Links/Headings views already do — no change to ElementsKind, the
  announcement code, or navigation.rs.

What changed

• paperback-core — new DocumentSession::element_list(mtype, position), returning one row
  per marker of a type with the text reading navigation announces, plus the row nearest the
  current position so the dialog can preselect it. link_list is now a thin wrapper over it.
  New ElementListItem/ElementList types and unit tests cover captions, the line-text
  fallback, closest-index tracking, and that ListItem markers don't leak into the Lists view.
• paperback — Tables and Lists entries in the View dropdown on both the Windows and the
  macOS/Linux (DataView) code paths. The two Rc<FlatView> arguments threaded through the
  toggle/double-click/OK handlers are grouped into a single FlatViews struct keyed by view, so
  a future flat view stays a one-entry change (the pattern the Pages view set up).

Two new translatable strings: "Tables" and "Lists" (they'll reach the translators through
the usual auto-translate workflow).

Testing

• Confirmed working on Windows (release build) with PDFs — tables and lists appear in the
  Elements dialog and jumps land correctly.
• cargo test -p paperback-core (663 tests) and cargo clippy pass.
• The macOS/Linux DataView half is edited symmetrically but was not compiled or run on this
  machine (Windows host) — it needs a check there before relying on it.