feat: switch default init from OpenRC to Dinit

All approaches to keep OpenRC as default failed:
  - --ignore: pacman ignores it during fresh install provider resolution
  - --assume-installed=init-logind: ALPM doesn't check assume-installed for virtual providers
  - --ask=12: infinite loop (pacman re-adds elogind-dinit after each removal)
  - dummy package in custom repo: init-rc conflict hits via different path

Dinit works because pacman --noconfirm naturally picks elogind-dinit
(alphabetically before elogind-openrc), pulling dinit-rc which has no
conflict. All inits (OpenRC, Runit, S6) remain selectable in the
online installer.

Changes:
  - buildiso: INITSYS='dinit', remove --assume-installed/--ask hacks
  - basestrap/main.py, packages/main.py: remove same hacks
  - profile.yaml: antergos-live-dinit for dinit, move openrc pkg to init-specific
  - packagechooser.conf (x2): default=Dinit, Dinit first in item list
  - packagechooser_dm.conf: *-dinit instead of *-openrc
  - README.md, README.pl.md, docs/*: update all OpenRC-first references
  - AGENTS.md: document dinit as default

buildiso

@@ -97,18 +97,7 @@ make_rootfs() {
             args+=(-P)
         fi
 
-        # Pre-tend init-logind is already provided so pacman's resolver
-        # skips provider selection entirely. Without this, --noconfirm
-        # picks elogind-dinit (alphabetically before elogind-openrc),
-        # pulling in dinit -> dinit-rc which conflicts with openrc.
-        # --ask 4 auto-answers YES to any residual conflict questions.
-        local pacman_extra_args=()
-        case "${INITSYS}" in
-            openrc|runit|s6) pacman_extra_args=("--assume-installed=init-logind") ;;
-        esac
-        pacman_extra_args+=("--ask=4")
-
-        basestrap "${basestrap_args[@]}" "${args[@]}" "${rootfs}" "${packages[@]}" --overwrite='*' "${pacman_extra_args[@]}"
+        basestrap "${basestrap_args[@]}" "${args[@]}" "${rootfs}" "${packages[@]}" --overwrite='*'
 
         copy_overlay "${root_overlay}" "${rootfs}"
 
@@ -360,6 +349,7 @@ use_dracut=false
 squash_only=false
 boot_only=false
 copy_pacconf=false
+INITSYS='dinit'
 
 basestrap_args=(-GMc)
 cmd=${0##*/}