feat(pm/shorthair): Add droidcam for phone webcam

packetmix/systems/shorthair/webcam.nix

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+# SPDX-FileCopyrightText: 2025 FreshlyBakedCake
+#
+# SPDX-License-Identifier: MIT
+
+{
+  programs.droidcam.enable = true;
+}