feat(win): Phase 4 — task manager (kill + PROTECTED allowlist)

[ronylicha]

Summary

• Real Windows kill_process via sysinfo Process::kill() (maps to TerminateProcess); replaces false stub. _force documented as moot — Windows has no graceful-signal analogue.
• Linux PROTECTED narrowed: #[cfg(not(target_os = "macos"))] → #[cfg(target_os = "linux")] (byte-identical body). Prevents accidentally giving Windows the Linux daemon list.
• Windows PROTECTED added (16 entries): kernel pseudo-processes (System, Registry, smss, csrss), session management (wininit, winlogon), services infrastructure (services, lsass, svchost, dwm, fontdrvhost), user shell (explorer, ctfmon, RuntimeBroker), self (freeyourdisk, FreeYourDisk).

Test plan

• Linux CI: cargo clippy -D warnings green (Linux/macOS arms unchanged)
• Windows CI: cargo check --target x86_64-pc-windows-msvc compiles the #[cfg(windows)] arm
• No new dependency added (sysinfo already a dep)
• PROTECTED const shape identical across all three OS arms (&[&str])