Port the selected AI removal scaffold for 4.0.3

Port only Remove > AI and T3 removal/tests from #7504 (023021ad2d). Keep Dictation in its baseline location and omit unrelated removers.

(cherry picked from commit 73480ffabc091b812a0cfbe7bc845799c6078a88)

test/shell.d/remove-ai-test.sh

@@ -0,0 +1,40 @@
+#!/bin/bash
+
+set -euo pipefail
+
+source "$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)/base-test.sh"
+
+tmp_dir="$(mktemp -d)"
+trap 'rm -rf "$tmp_dir"' EXIT
+
+mkdir -p "$tmp_dir/bin"
+
+cat >"$tmp_dir/bin/omarchy-pkg-drop" <<'SCRIPT'
+#!/bin/bash
+printf 'drop:%s\n' "$*" >>"$TEST_LOG"
+SCRIPT
+chmod +x "$tmp_dir/bin/omarchy-pkg-drop"
+
+export TEST_LOG="$tmp_dir/log"
+export PATH="$tmp_dir/bin:$PATH"
+
+fresh_home() {
+  rm -rf "$tmp_dir/home"
+  mkdir -p "$tmp_dir/home"
+  export HOME="$tmp_dir/home"
+}
+
+# T3 Code bootstraps the agents it drives; their state outlives it.
+fresh_home
+mkdir -p "$HOME/.config/t3code" "$HOME/.t3" "$HOME/.grok" "$HOME/.local/share/opencode" "$HOME/.npm"
+touch "$HOME/.claude.json"
+"$ROOT/bin/omarchy-remove-ai-t3-code" >/dev/null
+
+[[ ! -e $HOME/.t3 ]] || fail "T3 Code removal deletes its own data"
+pass "T3 Code removal deletes its own data"
+
+for kept in .grok .claude.json .npm .local/share/opencode; do
+  [[ -e $HOME/$kept ]] || fail "T3 Code removal keeps the agent state it bootstrapped" "$kept"
+done
+pass "T3 Code removal keeps the agent state it bootstrapped"
+