docs: README as overview + options, one docs page per feature

README keeps intro, feature list linking docs/, install, two sessions,
usage, the complete options table, changes outside Nix, rollback,
uninstall. Each feature's details (problem, what you get, configuration,
limitations, how it works) move to its own page in docs/; docs/dashboard.md
is split per feature and docs/changes-outside-nix.md becomes
docs/cleanup.md.

docs/launcher-menu.md

@@ -1,15 +1,73 @@
-# Launcher menu: how it works
+# Launcher menu
 
-Technical details of the "+" menu features. What they do and how to
-configure them: README, [launcher menu](../README.md#launcher-menu-launchermenu),
-[hidden apps](../README.md#hidden-apps-launchermenuhiddenapps),
-[icon fallbacks](../README.md#icon-fallbacks-launchermenuiconfallbacks).
+`launcherMenu.*`: the VR dashboard's "+" menu (non-Steam programs), with
+[hidden apps](#hidden-apps) and [icon fallbacks](#icon-fallbacks). Options:
+[README, Options](../README.md#options).
 
-## Menu patches
+## Problem
 
-`launcherMenu.*` (module `launcher-menu`): [UI patches](ui-patches.md) in
-Steam's `SharedJSContext` (`modules/launcher-menu/`), each registered only
-when its option is set and reverted by its unpatch when unset (next switch):
+The "+" menu is in random order with "Desktop" somewhere in a scrolling
+list, and a click shows no feedback until the window appears, so programs
+often get started twice.
+
+## What you get
+
+Patches of Steam's UI, each on its own option:
+
+- `sort`: programs sorted by name (case-insensitive), Desktop included.
+- `pinDesktop = "top"` / `"bottom"`: Desktop pinned above/below the list,
+  always visible.
+- `closeOnLaunch`: the menu closes on click.
+- `launchDebounceSeconds = <seconds>`: a repeat launch of the same command
+  within that time is ignored (and logged); a program that exits right away
+  can only be restarted once the time is up.
+- `grid.enable`: the programs section becomes a grid of tiles (icon, name
+  below); "Add desktop window" stays a list. The popup is 300 px wide, so
+  `grid.columns` sets the tile size (3 ≈ 92 px, 4 ≈ 68 px, 5 ≈ 53 px);
+  `grid.maxRows` limits visible rows, the rest scrolls.
+- `showAllApps`: every program, see
+  [below](#all-programs-and-developer-mode).
+
+All revert when turned off (next switch).
+
+## Configuration
+
+```nix
+steamFrame.launcherMenu = {
+  sort = true;
+  pinDesktop = "bottom";
+  closeOnLaunch = true;
+  launchDebounceSeconds = 10;
+  grid = { enable = true; columns = 4; maxRows = 4; };
+  showAllApps = true;
+  hiddenApps = [ "lxterminal" "cmake-gui" "firewall-config" "renderdoc" ];
+};
+```
+
+### All programs and Developer Mode
+
+Without Developer Mode Steam hides `konsole`, `systemsettings`, `dolphin`,
+`plasma-discover`, `vlc`, `firewall-config`, `cmake-gui`, `qrenderdoc`,
+`lxterminal` and `sh`. **Steam Developer Mode** (a Steam setting, not managed
+here) makes the "+" menu list every desktop entry; `showAllApps` lifts that
+filter only, so Developer Mode (sshd, xrdp, LAN DevTools forwards) can stay
+off. No feature needs Developer Mode; keep it off (see
+[DevTools on the LAN](ui-patches.md#devtools-on-the-lan)). Hide single
+programs with [`hiddenApps`](#hidden-apps).
+
+## Limitations
+
+- The pinned Desktop works with the laser but not with thumbstick / D-pad
+  navigation.
+- Tested with Steam client 1790377368. A Steam update can break the
+  patches; the menu then stays stock
+  ([after a Steam update](ui-patches.md#after-a-steam-update)).
+
+## How it works
+
+[UI patches](ui-patches.md) in Steam's `SharedJSContext`
+(`modules/launcher-menu/`, module `launcher-menu`), each registered only when
+its option is set and reverted by its unpatch when unset:
 
 - `order/`: sorts `ScanForInstalledNonSteamApps()` by name (Steam lists the
   programs in GLib hash-table order);
@@ -26,14 +84,46 @@ and verified by the [offline checker](ui-patches.md#after-a-steam-update).
 
 ## Hidden apps
 
-`launcherMenu.hiddenApps` (module `hidden-apps`): a Home Manager-linked
-desktop entry with `Hidden=true` per id in `~/.local/share/applications`,
-which masks the system entry of the same id for Steam and KDE alike.
+`launcherMenu.hiddenApps`, module `hidden-apps`.
+
+**Problem:** with Developer Mode or `showAllApps`, the "+" menu lists every
+desktop entry, including system tools.
+
+**What you get:** the listed desktop entry ids (no `.desktop`) are hidden
+from the "+" menu and the KDE menu. The "+" menu always hides `steam` and
+`vrurlhandler`; for Konsole in VR use
+[`showAllApps`](#all-programs-and-developer-mode).
+
+**How it works:** a Home Manager-linked desktop entry with `Hidden=true` per
+id in `~/.local/share/applications`, which masks the system entry of the
+same id for Steam and KDE alike.
 
 ## Icon fallbacks
 
-`launcherMenu.iconFallbacks.*`: Home Manager links nixpkgs' Breeze SVGs
-into `~/.local/share/icons/hicolor/scalable/apps/`. When the set of links
+`launcherMenu.iconFallbacks.*`. On by default.
+
+**Problem:** Steam resolves `Icon=` only in the hicolor theme (and
+`pixmaps`), so Konsole and KDE System Settings, whose icons only Breeze has,
+show without icon.
+
+**What you get:** Breeze's `utilities-terminal` and `preferences-system`
+icons (plus `extra`) in hicolor, so the "+" menu shows them. A running Steam
+picks up changes without a restart. Each switch also prints hints: icons of
+programs Steam can't find that Breeze has (add them to `extra`), and
+fallbacks hicolor has anyway.
+
+**Configuration:** `extra` adds Breeze icon names; a name Breeze doesn't have
+fails the build, `enable = false` provides none.
+
+```nix
+steamFrame.launcherMenu.iconFallbacks.extra = [ "system-file-manager" ];
+```
+
+`iconFallbacks` used to be a list; a list now fails with a hint (use
+`extra`, or `enable = false` for `[ ]`).
+
+**How it works:** Home Manager links nixpkgs' Breeze SVGs into
+`~/.local/share/icons/hicolor/scalable/apps/`. When the set of links
 changes, the switch bumps the mtime of `~/.local/share/icons/hicolor`, so a
 running Steam rescans (GTK only rereads a theme whose directory changed).
 The switch's hints come from `icon-fallbacks.sh`.