Merge nucleic/olive-ember-seal-q7vk into dev

packages/nash-default-shell/control

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+Package: nash-default-shell
+Version: @VERSION@
+Architecture: all
+Maintainer: Nucleic <[email protected]>
+Section: shells
+Priority: optional
+Depends: nash
+Description: force nash as the system default shell (NASH.md §7.1)
+ The maintainer-script form of the locked divert block: /bin/bash and /bin/dash
+ are dpkg-diverted to /usr/bin/{bash,dash}.real and /bin/{bash,dash,sh} point at
+ nash, so shebangs and tools that hardcode sh/bash land in nash. Real shells
+ stay reachable at the .real paths — nash's parse-failure fallback depends on
+ them. Removing this package cleanly restores stock shells. dpkg-divert keeps
+ apt upgrades of bash/dash from clobbering the links.

packages/nash-default-shell/files/etc/profile.d/naros-shell.sh

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+# narOS shell environment (nash-default-shell). NUCLEIC_REAL_BASH is nash's
+# parse-failure fallback + NUCLEIC_NASH_DISABLE target (NASH.md §4.1).
+export NUCLEIC_REAL_BASH=/usr/bin/bash.real
+[ -n "${SHELL:-}" ] || export SHELL=/usr/local/bin/nash

packages/nash-default-shell/postinst

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+#!/bin/sh
+# NASH.md §7.1, verbatim semantics (merged-usr symlink handling verified in nash M0).
+set -e
+if [ "$1" = "configure" ]; then
+    dpkg-divert --package nash-default-shell --divert /usr/bin/bash.real --rename --add /bin/bash
+    dpkg-divert --package nash-default-shell --divert /usr/bin/dash.real --rename --add /bin/dash
+    ln -sf /usr/local/bin/nash /bin/bash
+    ln -sf /usr/local/bin/nash /bin/dash
+    ln -sf /usr/local/bin/nash /bin/sh
+fi

packages/nash-default-shell/prerm

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+#!/bin/sh
+# Clean revert: drop the nash links, un-divert the real shells, restore sh -> dash.
+set -e
+if [ "$1" = "remove" ]; then
+    rm -f /bin/bash /bin/dash
+    dpkg-divert --package nash-default-shell --rename --remove /bin/bash
+    dpkg-divert --package nash-default-shell --rename --remove /bin/dash
+    ln -sf dash /usr/bin/sh
+fi