feat(privesc): migrate from opendoas to sudo-rs

doas's one-shot password and absent 'sudo -v' kept wasting hour-long
paru AUR builds. sudo-rs is a memory-safe Rust rewrite (ISRG/Ferrous
Systems), drop-in CLI compatible, and the same one Ubuntu 25.10 ships
as default. We follow the Arch wiki 'Using sudo-rs without the sudo
package' recipe verbatim — no custom shims.

- meta/base.txt: -doas-sudo-shim +sudo-rs
- etc/sudoers-rs (mode 0440): wiki minimal config + NOPASSWD reboot/poweroff
- etc/pam.d/sudo: 4-line copy of upstream sudo's PAM file
- run_onchange_after_deploy-etc.sh.tmpl: use real sudo, deploy sudoers-rs
  at 0440, create /etc/pam.d/sudo-i and /usr/local/bin/{sudo,sudoedit,
  su,visudo} → sudo-rs symlinks idempotently
- delete etc/doas.conf, dot_local/bin/{doasedit,sudo}
- zshrc: drop sudo=doas/sudoedit=doasedit aliases; rewrite ss/gimme/
  pacdiff/ssys to call sudo
- justfile: s/doas/sudo/g (status/diff/restore helpers)
- nvim: rename :DoasWrite → :SudoWrite (uses sudo -S)
- sway config: reboot/poweroff buttons call sudo
- bootstrap.sh: update step-5 comment
- README/KEYBINDS/copilot-instructions: flip the privesc convention

No Defaults overrides: sudo's defaults (passwd_tries=3,
timestamp_timeout=5) already fix the doas pain, and paru SudoLoop
(kept) refreshes the 5-min window via real sudo -v.

3 files changed, 17 insertions, 3 deletions

diff --git a/etc/doas.conf b/etc/doas.conf
deleted file mode 100644
index fad7c3c..0000000
--- a/etc/doas.conf
+++ /dev/null
@@ -1,3 +0,0 @@
-permit persist setenv { PATH TERM LANG LC_ALL EDITOR DIFFPROG PAGER } :wheel
-permit nopass :wheel as root cmd /usr/bin/poweroff
-permit nopass :wheel as root cmd /usr/bin/reboot
diff --git a/etc/pam.d/sudo b/etc/pam.d/sudo
new file mode 100644
index 0000000..ab053c5
--- /dev/null
+++ b/etc/pam.d/sudo
@@ -0,0 +1,4 @@
+#%PAM-1.0
+auth		include		system-auth
+account		include		system-auth
+session		include		system-auth
diff --git a/etc/sudoers-rs b/etc/sudoers-rs
new file mode 100644
index 0000000..8326b8e
--- /dev/null
+++ b/etc/sudoers-rs
@@ -0,0 +1,13 @@
+# Keep $EDITOR / $VISUAL when running visudo.
+Defaults!/usr/bin/visudo-rs    env_keep += "SUDO_EDITOR EDITOR VISUAL"
+Defaults!/usr/local/bin/visudo env_keep += "SUDO_EDITOR EDITOR VISUAL"
+
+# Sanitize PATH for elevated commands.
+Defaults secure_path="/usr/local/sbin:/usr/local/bin:/usr/bin"
+
+# Root and the wheel group can run anything (after a password prompt).
+root   ALL=(ALL:ALL) ALL
+%wheel ALL=(ALL:ALL) ALL
+
+# Passwordless poweroff/reboot (parity with the previous doas.conf).
+%wheel ALL=(ALL) NOPASSWD: /usr/bin/poweroff, /usr/bin/reboot