Seed default config on install; share defaults JSON with runtime

The defaults now live in a single file, scripts/config.default.json:

- src/config.ts imports it via 'with { type: "json" }' and derives
  DEFAULT_CONFIG (with seconds->ms conversion at the boundary), so the
  CLI help text always matches what the seeded user config contains.
- scripts/install.sh copies the same file to
  $XDG_CONFIG_HOME/move/config.json only if no file is already there.
  Existing configs (yours or from a previous install) are never
  overwritten.
- scripts/uninstall.sh does not touch the user config file at all,
  following the strict Unix convention. It does print a one-line
  notice pointing at the path so the user can rm -rf the dir
  themselves if they want a fully-clean removal.
- tsconfig.json gains resolveJsonModule:true so tsc accepts the JSON
  import.
- A small runtime assertion in src/config.ts (assertSeedShape) fails
  loudly if the seed file is missing keys or has wrong types.
- README Configuration section documents the seed behavior; Uninstall
  section documents the leave-config-behind policy with the rm-it-
  yourself command; Files table gains scripts/config.default.json.

scripts/uninstall.sh

@@ -8,10 +8,15 @@
 #
 # Removes the `move` wrapper from $XDG_BIN_HOME and the install tree from
 # $XDG_DATA_HOME/move. Does NOT remove Bun — that's your runtime, not ours.
+# Also leaves the user config file at $XDG_CONFIG_HOME/move/config.json
+# intact (Unix convention; user customizations are not ours to delete).
+# A notice is printed pointing at the file so you can remove it yourself
+# if desired.
 #
 # Env vars (must match what install.sh used):
-#   XDG_DATA_HOME Source install root (default $HOME/.local/share).
-#   XDG_BIN_HOME  Wrapper install root (default $HOME/.local/bin).
+#   XDG_DATA_HOME   Source install root (default $HOME/.local/share).
+#   XDG_BIN_HOME    Wrapper install root (default $HOME/.local/bin).
+#   XDG_CONFIG_HOME User config root (default $HOME/.config).
 #
 # POSIX sh; no bashisms.
 
@@ -19,6 +24,8 @@ set -eu
 
 INSTALL_DIR="${XDG_DATA_HOME:-$HOME/.local/share}/move"
 BIN_DIR="${XDG_BIN_HOME:-$HOME/.local/bin}"
+CONFIG_DIR="${XDG_CONFIG_HOME:-$HOME/.config}/move"
+CONFIG_FILE="$CONFIG_DIR/config.json"
 WRAPPER="$BIN_DIR/move"
 
 die() {
@@ -50,7 +57,16 @@ fi
 
 if [ "$REMOVED_SOMETHING" = "0" ]; then
     printf 'Nothing to remove. Checked %s and %s.\n' "$WRAPPER" "$INSTALL_DIR"
+    if [ -e "$CONFIG_FILE" ]; then
+        printf 'Note: config file at %s was left in place.\n' "$CONFIG_FILE"
+        printf '      Remove it manually with: rm -rf %s\n' "$CONFIG_DIR"
+    fi
     exit 0
 fi
 
+if [ -e "$CONFIG_FILE" ]; then
+    printf '\nNote: your config file at %s was left in place.\n' "$CONFIG_FILE"
+    printf '      Remove it manually with: rm -rf %s\n' "$CONFIG_DIR"
+fi
+
 printf '\nUninstalled. (Bun was not touched.)\n'