move SSH key decryption from provision.sh to on_start.sh

Keys now install to /root/.ssh/ (for root git operations) instead of
/data/ssh/.ssh/. Runs every boot via on_start.sh so keys are available
even without a full provision cycle.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

system/clearpilot/on_start.sh

@@ -9,6 +9,23 @@ echo -n 1 > /data/params/d/SshEnabled
 sudo systemctl enable ssh 2>/dev/null
 sudo systemctl start ssh
 
+# Decrypt and install SSH identity keys for root (git auth)
+serial=$(sed 's/.*androidboot.serialno=\([^ ]*\).*/\1/' /proc/cmdline)
+ssh_dir="/root/.ssh"
+if [[ $serial == 3889765b ]] && [[ ! -f "$ssh_dir/id_ed25519" || ! -f "$ssh_dir/id_ed25519.pub" ]]; then
+    echo "Decrypting SSH identity keys for root (serial=$serial)..."
+    tmpdir=$(mktemp -d)
+    bash /data/openpilot/system/clearpilot/tools/decrypt /data/openpilot/system/clearpilot/dev/id_ed25519.cpt "$tmpdir/id_ed25519"
+    bash /data/openpilot/system/clearpilot/tools/decrypt /data/openpilot/system/clearpilot/dev/id_ed25519.pub.cpt "$tmpdir/id_ed25519.pub"
+    sudo mkdir -p "$ssh_dir"
+    sudo cp "$tmpdir/id_ed25519" "$tmpdir/id_ed25519.pub" "$ssh_dir/"
+    rm -rf "$tmpdir"
+    sudo chmod 700 "$ssh_dir"
+    sudo chmod 600 "$ssh_dir/id_ed25519"
+    sudo chmod 644 "$ssh_dir/id_ed25519.pub"
+    echo "SSH identity keys installed to $ssh_dir"
+fi
+
 # Always ensure WiFi radio is on
 nmcli radio wifi on 2>/dev/null