fix(iso-visuals): avoid host-global tmp in wallpaper helper (Sam & Pi)

Sync the wallpaper helper and iso-visuals guidance with the project-local tmp policy, falling back to app-owned live cache paths when no project root exists.\n\nValidation: sh -n skills/iso-visuals/scripts/clawdie-wallpaper-gen.sh skills/iso-visuals/scripts/clawdie-join-hive.sh; npx --yes prettier@3 --check skills/iso-visuals/SKILL.md; python3 scripts/layered_soul.py validate .

skills/iso-visuals/SKILL.md

@@ -70,15 +70,20 @@ install -m 755 scripts/clawdie-wallpaper-gen.sh \
 ```
 
 The helper falls back to the stock XFCE background, then to a generated dark solid
-background under `/tmp`. It should not try to create files under `/usr/local/share`
+background under project-local `tmp/` when a checkout is available. On the live USB,
-at runtime unless explicitly requested by the operator.
+where there is usually no project root, it uses an app-owned cache directory such as
+`$XDG_CACHE_HOME/clawdie` or `$HOME/.cache/clawdie`. It should not try to create
+files under `/usr/local/share` at runtime unless explicitly requested by the operator.
 
 **Optional runtime/session wiring:**
 
 ```bash
-/usr/local/bin/clawdie-wallpaper-gen /tmp/clawdie-wallpaper.png
+PROJECT_ROOT=$(git rev-parse --show-toplevel)
+PROJECT_TMP="$PROJECT_ROOT/tmp"
+mkdir -p "$PROJECT_TMP"
+/usr/local/bin/clawdie-wallpaper-gen "$PROJECT_TMP/clawdie-wallpaper.png"
 xfconf-query -c xfce4-desktop -p /backdrop/screen0/monitor0/workspace0/last-image \
-  -s /tmp/clawdie-wallpaper.png
+  -s "$PROJECT_TMP/clawdie-wallpaper.png"
 ```
 
 Requires ImageMagick (`ImageMagick7` in the ISO package list; `magick` or
@@ -166,7 +171,8 @@ After booting the ISO:
    reports provider.env status without exposing secrets, registers or reports
    already registered, then waits for Enter.
 4. **Wallpaper helper:** running `/usr/local/bin/clawdie-wallpaper-gen` writes an
-   image to `/tmp/clawdie-wallpaper.png` using the Clawdie wallpaper as base.
+   image under project-local `tmp/` when run from a checkout, or an app-owned live
+   cache directory when no project root exists, using the Clawdie wallpaper as base.
 5. **Panel indicator helper:** running `/usr/local/bin/colibri-panel-indicator`
    prints genmon XML. Only claim panel visibility after genmon is packaged and
    wired into the seeded panel or configured manually.

skills/iso-visuals/scripts/clawdie-wallpaper-gen.sh

@@ -1,17 +1,40 @@
 #!/bin/sh
 # Generate a wallpaper with machine identity overlaid.
-# Safe to run on first boot; caches result in /tmp/clawdie-wallpaper.png.
+# Safe to run on first boot; caches result in project-local tmp/ when a project
+# root is available, otherwise in the live user's app-owned cache directory.
 # Requires ImageMagick (magick or convert). Tailscale is optional.
 
-OUT="${1:-/tmp/clawdie-wallpaper.png}"
 CLAWDIE_BG="/usr/local/share/clawdie-iso/wallpapers/clawdie-operator-bg.png"
 XFCE_BG="/usr/local/share/backgrounds/xfce/default.png"
-FALLBACK_BG="/tmp/clawdie-wallpaper-base.png"
 
 have() {
     command -v "$1" >/dev/null 2>&1
 }
 
+project_root() {
+    if [ -n "${CLAWDIE_PROJECT_ROOT:-}" ]; then
+        printf '%s\n' "$CLAWDIE_PROJECT_ROOT"
+    elif have git && git rev-parse --show-toplevel >/dev/null 2>&1; then
+        git rev-parse --show-toplevel
+    else
+        return 1
+    fi
+}
+
+scratch_dir() {
+    if [ -n "${CLAWDIE_TMP:-}" ]; then
+        printf '%s\n' "$CLAWDIE_TMP"
+    elif _root=$(project_root); then
+        printf '%s/tmp\n' "$_root"
+    elif [ -n "${XDG_CACHE_HOME:-}" ]; then
+        printf '%s/clawdie\n' "$XDG_CACHE_HOME"
+    elif [ -n "${HOME:-}" ]; then
+        printf '%s/.cache/clawdie\n' "$HOME"
+    else
+        printf '%s\n' "/var/cache/clawdie"
+    fi
+}
+
 if have magick; then
     im() { magick "$@"; }
 elif have convert; then
@@ -21,6 +44,11 @@ else
     exit 1
 fi
 
+SCRATCH_DIR=$(scratch_dir)
+mkdir -p "$SCRATCH_DIR"
+OUT="${1:-${SCRATCH_DIR}/clawdie-wallpaper.png}"
+FALLBACK_BG="${SCRATCH_DIR}/clawdie-wallpaper-base.png"
+
 HOST=$(hostname 2>/dev/null || echo "clawdie-live")
 if have tailscale; then
     TS_IP=$(tailscale ip -4 2>/dev/null | head -n 1)