feat(dev): open browser automatically on dev server ready

Polls /auth/dev-login until the app responds, then opens an incognito/private
window — same pattern as padelnomics. Tries flatpak Chrome → flatpak Firefox
→ system Chrome → Chromium → Firefox in that order.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/scripts/dev_run.sh

@@ -165,4 +165,27 @@ run_with_label "$COLOR_APP"    "app   " uv run --package beanflows python -m bea
 run_with_label "$COLOR_WORKER" "worker" uv run --package beanflows python -m beanflows.worker
 run_with_label "$COLOR_CSS"    "css   " make css-watch
 
+# Open a private/incognito browser window once the server is ready.
+# Polls /auth/dev-login until it responds (up to 10 seconds), then launches.
+(
+    DEV_URL="http://localhost:5001/auth/dev-login?email=pro@beanflows.coffee"
+    for i in $(seq 1 20); do
+        sleep 0.5
+        if curl -s -o /dev/null -w "%{http_code}" "$DEV_URL" 2>/dev/null | grep -qE "^[23]"; then
+            break
+        fi
+    done
+    if flatpak info com.google.Chrome >/dev/null 2>&1; then
+        flatpak run com.google.Chrome --incognito "$DEV_URL" &>/dev/null &
+    elif flatpak info org.mozilla.firefox >/dev/null 2>&1; then
+        flatpak run org.mozilla.firefox --private-window "$DEV_URL" &>/dev/null &
+    elif command -v google-chrome >/dev/null 2>&1; then
+        google-chrome --incognito "$DEV_URL" &>/dev/null &
+    elif command -v chromium >/dev/null 2>&1; then
+        chromium --incognito "$DEV_URL" &>/dev/null &
+    elif command -v firefox >/dev/null 2>&1; then
+        firefox --private-window "$DEV_URL" &>/dev/null &
+    fi
+) &
+
 wait