v0.4.1 — Theme, memory-access, and packaging fixes

Bug-fix release on top of v0.4.0.

Fixes

• Light/dark theme now works. Toggling "Dark theme" in Settings applies live
  (no restart), and the startup default and the Settings checkbox agree (both
  default to light). The two stylesheets moved into a shared gui/theme module so
  startup and the dialog use the same sheets.
• Memory browser no longer fails silently. When a process can't be read
  because of the kernel's ptrace policy (kernel.yama.ptrace_scope), the
  disassembler shows a clear explanation instead of a blank pane, and opening such
  a process pops a warning naming the exact remedies. This is why "browse memory"
  appeared to work only on some processes.

Packaging

• Automatic ptrace access. The .deb now runs setcap cap_sys_ptrace+ep on
  the installed binaries at install time (via a postinst; depends on libcap2-bin),
  so scanning/browsing/debugging works without running as root. For AppImage or
  ad-hoc runs, the "process not readable" dialog has a one-click Grant access…
  button (via pkexec).
• Working AppImage. The AppImage is now built with linuxdeploy + the Qt plugin,
  so it bundles the Qt platform plugins and actually runs (the earlier hand-rolled
  bundle was missing them).

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Install (.deb, recommended): grants memory-access rights automatically —
sudo apt install ./cheat-engine-linux_0.4.1_amd64.deb

AppImage: chmod +x CheatEngine-0.4.1-x86_64.AppImage && ./CheatEngine-0.4.1-x86_64.AppImage
(if a process shows no memory, use the in-app "Grant access…" button).