gridcull: thumbnail TMS cache, grid view, trash, window d/D/u/t (jt0)

M7 (task jt0): thumbnail cache + grid view + trash.

- src/trash.{c,h}: ./Trash bin (lazy create, collision suffix -1/-2, restore_last
  for u undo, permanent delete for D). Plain-C, unit-tested.
- src/thumbnail.{c,h}: freedesktop TMS cache (normal/large/x-large buckets,
  md5(URI) key, Thumb::URI/MTime/Size, mtime verify). Async GTask worker with
  GCancellable so the grid can cancel pending requests on dispose.
- src/gridview.{c,h}: GgazeGrid (GtkWidget wrapping GtkFlowBox): one cell per
  navigator file, lazy thumbnail decode on realize, +/- resize 64-512, dim
  removed cells, mark badges, Enter/double-click → 'activate' signal, cursor
  sync. ggaze_grid_detach() breaks the nav ref before dispose.
- src/navigator.{c,h}: removed set (mark_removed/is_removed/unmark_removed);
  _relist preserves removed items (stay dimmed even if absent from disk);
  get_remaining = count - removed_count.
- src/window.c: d (trash+mark_removed+advance), D (permanent delete, confirm
  dialog if >1 marked), u (restore_last+rescan), t (toggle grid/large),
  +/- (viewer zoom in large / grid resize). Header counter uses remaining.
- src/shortcuts.c: d/D/u/t/+/= bindings added.
- tests: unit test_trash + test_thumbnail, integration test_grid_cull
  (grid count + trash/undo + ./sample-images 613-cell grid). 13/13 green,
  ASan clean.

Fixed: grid dispose UAF (detach before nav freed), g_file_get_basename leak,
test p_plain lifetime, thumbnail async-cancellable for clean dispose, test
grid-toggle avoiding async-thumbnail drain issues.

1 files changed, 43 insertions, 0 deletions

diff --git a/src/trash.h b/src/trash.h
new file mode 100644
index 0000000..e190263
--- /dev/null
+++ b/src/trash.h
@@ -0,0 +1,43 @@
+#ifndef GGAZE_TRASH_H
+#define GGAZE_TRASH_H
+
+/*:*
+ * ggaze — local ./Trash bin
+ *
+ * Moves files into <shoot_dir>/.Trash/ (created lazily, collision-suffixed
+ * -1/-2/...) and tracks the last binned item for `u` restore. `D` permanently
+ * unlinks. Never touches the system trash. Plain-C, no GtkWidget,
+ * unit-testable. See docs/architecture.md "trash" + docs/PLAN.md decisions
+ * #5/#6.
+ *
+ * Copyright (c) 2026 ggaze contributors
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *:*/
+
+#include <gio/gio.h>
+#include <glib.h>
+
+G_BEGIN_DECLS
+
+typedef struct Trash Trash;
+
+/* .Trash lives at <p_shoot_dir>/.Trash. Refs p_shoot_dir. */
+Trash *trash_new(GFile *p_shoot_dir);
+void   trash_delete(Trash *p_t); /* g_object_unref-style destructor */
+
+/* Move p_file into .Trash (lazy create, collision suffix -1/-2). Records the
+ * move so trash_restore_last() can undo it. Returns TRUE on success. */
+gboolean trash_bin(Trash *p_t, GFile *p_file, GError **p_err);
+
+/* Permanently delete p_file (unlink). Not undoable. */
+gboolean trash_permanently_delete(Trash *p_t, GFile *p_file, GError **p_err);
+
+/* Move the last binned file back to its original path. Returns FALSE if there
+ * is nothing to undo. */
+gboolean trash_restore_last(Trash *p_t, GError **p_err);
+
+gboolean trash_can_undo(Trash *p_t);
+
+G_END_DECLS
+
+#endif /* GGAZE_TRASH_H */
\ No newline at end of file