Phase 0: strip JetBrains template, register Jai language and file type

- delete demo tool window + message bundle, rewrite plugin.xml metadata
- add JaiLanguage, JaiFileType, file icon, JaiTokenTypes (from the compiler's
  own lexer: modules/Jai_Lexer/module.jai)
- add ./jaitest: runs tests and reports the JUnit XML, not just the exit code
- ignore .kotlin

jaitest

@@ -0,0 +1,46 @@
+#!/usr/bin/env bash
+# Run the test suite and report the JUnit XML, not just the exit code.
+#
+# A green `test` task does not prove tests ran (see AGENTS.md), so this always
+# prints tests/failures/errors per suite and dumps failure messages.
+#
+# Usage: ./jaitest [gradle args...]      e.g. ./jaitest --tests '*Lexer*'
+set -uo pipefail
+
+cd "$(dirname "$0")" || exit 1
+
+rm -rf build/test-results/test
+./jaigradle test "$@" 2>&1 | grep -vE '^\[[0-9.]+s\]\[warning\]\[cds\]'
+gradle_status=${PIPESTATUS[0]}
+
+echo
+echo "=== JUnit XML ==="
+shopt -s nullglob
+xml=(build/test-results/test/*.xml)
+if [ ${#xml[@]} -eq 0 ]; then
+    echo "NO TEST XML PRODUCED — tests did not run."
+    exit 1
+fi
+
+total=0
+bad=0
+for f in "${xml[@]}"; do
+    line=$(sed -n '2p' "$f")
+    name=$(sed -nE 's/^<testsuite name="([^"]*)".*/\1/p' <<<"$line")
+    t=$(sed -nE 's/.*tests="([0-9]*)".*/\1/p' <<<"$line")
+    fa=$(sed -nE 's/.*failures="([0-9]*)".*/\1/p' <<<"$line")
+    er=$(sed -nE 's/.*errors="([0-9]*)".*/\1/p' <<<"$line")
+    sk=$(sed -nE 's/.*skipped="([0-9]*)".*/\1/p' <<<"$line")
+    printf '%-60s tests=%s skipped=%s failures=%s errors=%s\n' "$name" "$t" "$sk" "$fa" "$er"
+    total=$((total + t))
+    bad=$((bad + fa + er))
+    if [ "$fa" != "0" ] || [ "$er" != "0" ]; then
+        grep -E '<(failure|error) ' "$f" | head -40
+    fi
+done
+
+echo "--- total tests=$total failures+errors=$bad gradle_exit=$gradle_status"
+if [ "$total" -eq 0 ] || [ "$bad" -ne 0 ] || [ "$gradle_status" -ne 0 ]; then
+    exit 1
+fi
+echo "OK"