Fix desktop icons v1 regressions: bar overlap, wrong order; add proper menus

Live testing found v1 genuinely broken, not just rough:

1. Icons weren't rendering reliably at all - ensure_desktop_icons only
   ever computed the grid's origin once, on whichever render pass
   happened to be first. AGS's own top bar registers its exclusive zone
   after that first pass, so origin got permanently baked in at the
   pre-bar geometry. Confirmed live via a temporary diagnostic log.
   Fixed by re-deriving origin from the primary monitor's current
   geometry on every call instead of just the first.

2. Fixed icons (Home/Computer/Trash) always sorted before real files --
   confirmed wrong via direct question. The whole list now sorts
   alphabetically by label, case-insensitive, fixed icons included.

3. "Set as Wallpaper" was the wrong feature: removed entirely
   (DesktopMenuAction::SetWallpaper, general.wallpaper_command,
   is_image_path). The user wants that handled by their real file
   manager once opened, not reimplemented here.

Also adds real menu functionality per "where are all the options":
Rename (inline text edit, new CompState::renaming_icon field and
keyboard redirect mirroring NativeLock::password's existing precedent),
Delete (moves to ~/.local/share/Trash per the freedesktop.org spec, new
trash.rs module, same-filesystem case, no confirmation - this is the
reversible move-to-trash, not a permanent delete), Empty Trash on the
Trash icon, and Open Terminal Here / Open in File Manager on the
bare-desktop menu (new general.terminal config key).

133 wayland-crate tests (up from 106), full workspace build and clippy
clean.

1 files changed, 41 insertions, 19 deletions

diff --git a/docs/DEFAULTS.md b/docs/DEFAULTS.md
index 5f99446..2597840 100644
--- a/docs/DEFAULTS.md
+++ b/docs/DEFAULTS.md
@@ -20,7 +20,7 @@ srd.set("general.gpu", false)                          -- Default: false - udev
 srd.set("general.desktop_icons", true)                 -- Default: true - see "Desktop icons" below
 srd.set("general.file_manager", "")                    -- Default: "" - empty means dispatch via `xdg-open`
 srd.set("general.desktop_icon_single_click", false)    -- Default: false - double-click opens an icon
-srd.set("general.wallpaper_command", "")               -- Default: "" - empty hides "Set as Wallpaper" entirely
+srd.set("general.terminal", "")                        -- Default: "" - empty tries a common terminal on $PATH
 ```
 `general.smart_placement`/`general.border_width` are not listed: neither
 is implemented - new-window placement always uses smart placement
@@ -73,29 +73,51 @@ capability exists anywhere in this codebase, so folder/computer/trash/file
 icons are simple flat shapes, the same technique the titlebar's own
 buttons use.
 
+Icons sort into one alphabetical list by label, case-insensitive - the
+three fixed shortcuts interleave with real filenames rather than always
+coming first, e.g. "Computer" and "Documents" and "Home" and "Trash" sort
+exactly where their names put them.
+
 Double-click (or a single click when `general.desktop_icon_single_click`
-is `true`) opens an icon: `$general.file_manager <path>` if that key is
+is `true`) opens an icon: `general.file_manager <path>` if that key is
 set, otherwise `xdg-open <path>`. Dragging an icon snaps it to the nearest
 free grid cell on release and persists that cell to
 `$XDG_STATE_HOME/srd/desktop-icons.json` (else `~/.local/state/srd/...`) --
 only icons the user has actually moved get an entry there; everything
-else keeps recomputing its default slot on every rescan.
-
-Right-click an icon: "Open", plus "Set as Wallpaper" when it's an image
-file (`.png`/`.jpg`/`.jpeg`/`.webp`/`.bmp`/`.gif`) and `general.
-wallpaper_command` is set - shells out to `<wallpaper_command> <path>`.
-srdwm never draws the wallpaper itself (an external layer-shell client's
-job - `swww`, `awww`, or similar), so there is no universal default to
-guess here the way `xdg-open` covers `file_manager`; this action simply
-doesn't appear when the key is empty. Right-click bare desktop: "New
-Folder" (creates `~/Desktop/New Folder`, de-duplicated as `New Folder
-(2)`, `(3)`, ...) and "Refresh" (re-scans `~/Desktop`).
-
-Not implemented in this first pass, deliberately: moving a file to trash,
-emptying the trash, filesystem watching (a file added to `~/Desktop` by
-another program needs "Refresh" or a restart to appear), multi-select,
-and per-mimetype icon art. The first two are destructive/hard-to-reverse
-actions with no confirmation-dialog primitive to gate them on yet.
+else keeps recomputing its default slot on every rescan. The grid's own
+origin is re-derived from the primary monitor's current usable geometry
+every frame, so it always sits clear of a bar/dock's reserved strip on
+whichever edge it's anchored to, even if that reservation only appears
+after srdwm's first render (a real startup race with panels like AGS
+that connect and register their own exclusive zone after the compositor
+is already up).
+
+Right-click an icon: a real file or folder gets **Open**, **Rename**
+(inline, Enter to commit/Escape to cancel), and **Delete** (moves it to
+`~/.local/share/Trash` per the freedesktop.org Trash spec, same-filesystem
+case only - no confirmation prompt, since this is the reversible move-to-
+trash, not a permanent delete, the same convention every mainstream file
+manager uses). **Home**/**Computer** get **Open** only - they're
+shortcuts, not real files, so rename/delete don't apply. **Trash** gets
+**Open** and **Empty Trash** (also no prompt, same reversibility
+framing - this is the intentional final step, not a slip). Right-click
+bare desktop: **New Folder** (creates `~/Desktop/New Folder`, de-
+duplicated as `New Folder (2)`, `(3)`, ...), **Open Terminal Here**
+(`general.terminal`, or the first of alacritty/kitty/wezterm/foot/gnome-
+terminal/konsole/xterm found on `$PATH`, with `~/Desktop` as its working
+directory), **Open in File Manager** (opens `~/Desktop` itself in
+`general.file_manager`/`xdg-open` - the concrete path to a real file
+manager's own richer menu: cut/copy/paste, properties, set-as-wallpaper,
+deliberately not reimplemented here), and **Refresh** (re-scans
+`~/Desktop`).
+
+Not implemented, deliberately: Cut/Copy/Paste (real interop with a file
+manager needs the Wayland `wl_data_device`/`text/uri-list` clipboard
+protocol, a separate substantial feature - an srdwm-only internal
+clipboard wouldn't achieve real interop anyway), filesystem watching (a
+file added to `~/Desktop` by another program needs "Refresh" or a restart
+to appear), multi-select, View/Sort submenus (no nested-menu UI exists),
+and icons on any monitor but the primary one.
 
 ### Monitor Settings (`monitor.*`)
 ```lua