feat: switch to /usr layout and add dynamic dependency detection

- Move binaries to /usr/bin and /usr/libexec for system integration
- Add find-deps.sh script to detect required system packages from .so
  files
- Update Makefile to generate Depends field dynamically using apt-file
- Add list-deps target to Makefile for dependency analysis
- Update README with new usage, features, and instructions
- Update CI workflow to install apt-file and update its database

postrm

@@ -0,0 +1,11 @@
+#!/bin/sh
+set -e
+if [ "$1" = "remove" ] || [ "$1" = "purge" ]; then
+    if command -v gtk-update-icon-cache >/dev/null 2>&1; then
+        gtk-update-icon-cache -q -t -f /usr/share/icons/hicolor || true
+    fi
+    if command -v update-desktop-database >/dev/null 2>&1; then
+        update-desktop-database -q /usr/share/applications || true
+    fi
+fi
+exit 0