Make the row checkbox select items instead of ticking them off

The checkbox was marking items done, but the intent was to gather items
and act on them: tick several, then right-click to copy, copy as a list,
move, merge or delete them all at once. Done is still available from the
same menu, it is just no longer what the checkbox does.

AGENTS.md

@@ -27,13 +27,17 @@ clicking an item copies it back to the clipboard.
   `Images/` next to it, cached in an `NSCache`. Owns all mutations (add,
   toggle done, edit, delete, move, merge, clear done) and clipboard writes
   (`copy`, `copyAsList` for numbered output, `copyAsLines` for plain newlines;
-  both text modes skip image items). Saves on every mutation.
+  both text modes skip image items). Batch mutations (`delete(ids:)`,
+  `setDone(_:ids:)`, `move(ids:to:)`) back the selection context menu, so one
+  action applies to every selected item and image files are cleaned up once.
+  Saves on every mutation.
 - `Sources/Prompt/PanelView.swift` — the panel UI. Header (section switcher,
   search, add photos, close), item list, composer. Composer `# Name` creates/
-  switches sections. Click = copy; Cmd+click toggles multi-select, Shift+click
-  selects a range, and a selection bar offers Copy as List / Copy as Lines;
-  right-click = context menu (Copy, Copy as List, Copy as Lines, Done, Edit,
-  Open, Merge, Move To, Delete). Esc clears the selection before it hides the
+  switches sections. Click = copy; the row checkbox selects, Cmd+click toggles
+  multi-select, Shift+click selects a range, and a selection bar offers Copy as
+  List / Copy as Lines; right-click = context menu acting on the selection
+  (Copy, Copy as List, Copy as Lines, Done, Edit, Open, Merge, Move To,
+  Delete). Esc clears the selection before it hides the
   panel. Drop target for images/files.
 - `Sources/Prompt/PanelController.swift` — owns the floating `NSPanel`
   (`.nonactivatingPanel`, `.floating`, right-edge docked, frame autosaved as
@@ -169,8 +173,10 @@ brew upgrade --cask prompt
   clipboard image to the store when there is no text. `Prompt --diag` dumps the
   menu so the wiring can be checked without a keyboard.
 - **A row is not a `Button`** because it contains a checkbox `Button` for
-  ticking items off, and nested buttons never receive clicks. The row uses
-  `contentShape` + `onTapGesture` for click-to-copy instead.
+  selecting the item, and nested buttons never receive clicks. The row uses
+  `contentShape` + `onTapGesture` for click-to-copy instead. Selection is
+  driven by the checkbox, Cmd+click (toggle) and Shift+click (range); the
+  context menu acts on the whole selection via `effectiveIDs(for:)`.
 - **Never bind bare keys as `.keyboardShortcut` in the panel** (Space, Delete,
   plain Cmd+C). SwiftUI key equivalents are matched before text input and
   would steal characters from the composer TextField. Only Cmd-modified