Add purge and an uninstaller, and move to the stores org

`purge` removes every title this store installed, then the playlists, the
thumbnail folders and the store's own directories — what a shell script cannot
do, because only state.json knows which files were ours. uninstall.sh runs it
before deleting the launcher and the store home, and stops if the engine cannot
finish, so you are never left with the files but not the engine that knew about
them.

What survives on purpose: content you put in the store's folder (directories go
only when empty), and a playlist that still holds an entry of yours — only items
pointing inside the store's content folder are dropped, and a playlist that ends
up empty is deleted while one that does not is rewritten without us.

A playlist backup is no longer made while purging. It was being created on the
uninstall's first touch of a playlist we had written ourselves, which meant the
run reported a backup it had just made — and described it as possibly holding
entries that were never ours, which was the opposite of true.

install.sh and uninstall.sh are POSIX sh now, checked with dash, so `curl … | sh`
works where /bin/sh is not bash. The repository moved from the tools org to
stores; the old raw URLs still redirect, but every reference is updated.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

README.md

@@ -9,7 +9,7 @@ any particular site: the host, the store's name and where its games land all com
 from a `config.json` that lives in a separate **store repository**. The shared
 part — catalog, releases, state, HTTP — is
 [`warpstore`](https://git.teletypegames.org/engines/warpstore), which this engine
-has in common with the [Batocera engine](https://git.teletypegames.org/tools/warp-engine-batocera-store).
+has in common with the [Batocera engine](https://git.teletypegames.org/stores/warp-engine-batocera-store).
 
 ```
 warpstore                     the shared core
@@ -23,7 +23,7 @@ teletypegames.org
 ```
 
 The reference store is
-[`ttg-retroarch-store`](https://git.teletypegames.org/tools/ttg-retroarch-store).
+[`ttg-retroarch-store`](https://git.teletypegames.org/stores/ttg-retroarch-store).
 
 ```
 <store>-retroarch-store sync
@@ -66,8 +66,8 @@ trigger: the sync runs from a shell or from a scheduler.
 The installer takes the store as a parameter, so it works with any config:
 
 ```sh
-STORE_CONFIG=https://git.example.org/tools/my-store/raw/branch/master/config.json \
-  bash <(curl -fsSL https://git.teletypegames.org/tools/warp-engine-retroarch-store/raw/branch/master/install.sh)
+curl -fsSL https://git.teletypegames.org/stores/warp-engine-retroarch-store/raw/branch/master/install.sh |
+  STORE_CONFIG=https://git.example.org/tools/my-store/raw/branch/master/config.json sh
 ```
 
 From a checkout, with a local config:
@@ -103,6 +103,7 @@ $S sync                 # download everything new, refresh the playlists
 $S sync blessingofra    # just one title (never prunes)
 $S -n sync              # dry run
 $S remove c64:c64demo   # uninstall (bare name works too)
+$S purge                # uninstall everything this store installed
 $S config               # effective configuration
 ```
 
@@ -116,6 +117,45 @@ memory and writes them back when it exits — favourites, last played, sort orde
 so writing underneath it can be undone. Close it, or pass `--force` if you know
 what you are doing (`behavior.refuse_while_running: false` to stop asking).
 
+## Uninstalling
+
+```sh
+curl -fsSL https://git.teletypegames.org/stores/warp-engine-retroarch-store/raw/branch/master/uninstall.sh | sh
+```
+
+or `./uninstall.sh` from a checkout. It removes the games first, through the
+engine — `purge` — and only then the launcher and the store home: the shell
+script has no way of knowing which playlists, thumbnails and content files were
+the store's, and the engine's `state.json` does. If the engine cannot finish
+(RetroArch running, a directory gone) nothing else is touched, so you are never
+left with the files but not the engine that knows about them.
+
+| Environment variable | Meaning |
+|---|---|
+| `STORE_ID` | which store to remove; needed only when several are installed |
+| `STORE_CONFIG` | alternative to `STORE_ID` — the id is read out of the config |
+| `DRY_RUN` | `1` to print what would go and remove nothing |
+| `KEEP_HOME` | `1` to keep the store home (state, catalog cache, log) for a reinstall |
+| `FORCE` | `1` to purge even while RetroArch is running |
+| `STORE_ROOT`, `BIN_DIR` | as for the installer |
+
+What it deliberately leaves behind:
+
+- **content you put in the store's folder yourself.** Directories are removed only when empty, so one stray file keeps its directory.
+- **a playlist that still has entries of yours.** Only items pointing inside the store's content folder are dropped; a playlist that ends up empty is deleted, one that does not is rewritten without us.
+- **`*.lpl.<store id>-backup`**, listed at the end of the run. Those are the playlists as we first found them, so they can hold entries that were never ours — deleting them is your call.
+
+A dry run cannot predict which directories will end up empty, so it lists the
+files but not the directory removals.
+
+To take **every** store off a machine — both engines, the shared core, the
+launchers — there is one script for that in
+[`warpstore`](https://git.teletypegames.org/engines/warpstore):
+
+```sh
+curl -fsSL https://git.teletypegames.org/engines/warpstore/raw/branch/master/uninstall.sh | sh
+```
+
 ## Where things land
 
 ```
@@ -240,12 +280,13 @@ open question.
 
 ## Writing a store repository
 
-Three files:
+Four small files:
 
 ```
 my-retroarch-store/
 ├── config.json     the store: URL, name, subfolder, platform → core mapping
 ├── install.sh      a wrapper that hands that config to the engine installer
+├── uninstall.sh    the same for the engine's uninstaller
 └── README.md
 ```
 
@@ -254,9 +295,17 @@ my-retroarch-store/
 ```sh
 #!/bin/bash
 set -euo pipefail
-ENGINE_RAW_BASE="${ENGINE_RAW_BASE:-https://git.teletypegames.org/tools/warp-engine-retroarch-store/raw/branch/master}"
+ENGINE_RAW_BASE="${ENGINE_RAW_BASE:-https://git.teletypegames.org/stores/warp-engine-retroarch-store/raw/branch/master}"
 export STORE_CONFIG="${STORE_CONFIG:-https://git.example.org/tools/my-retroarch-store/raw/branch/master/config.json}"
-curl -fsSL "$ENGINE_RAW_BASE/install.sh" | bash
+curl -fsSL "$ENGINE_RAW_BASE/install.sh" | sh
+```
+
+`uninstall.sh` is the same shape, except that it passes `STORE_ID` — no config
+fetch is needed to take a store away, and the id is what names its home:
+
+```sh
+export STORE_ID="${STORE_ID:-example}"
+curl -fsSL "$ENGINE_RAW_BASE/uninstall.sh" | sh
 ```
 
 Pick a `store.id` and a `paths.subfolder` nobody else uses — they are what keeps