test: lmsensors extend unit tests, vendored framework [#769]

Moved from KNEL/PFVCluster tests/unit with repo-relative paths.

https://projects.knownelement.com/issues/769#note-4152

tests/unit/lmsensors-numeric.sh

@@ -0,0 +1,64 @@
+#!/bin/bash
+# Unit tests for lmsensors-extend.sh -n numeric mode [#618]
+set -euo pipefail
+
+PROJECT_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
+SCRIPT="$PROJECT_ROOT/sensors/temper/lmsensors-extend.sh"
+
+failed=0
+if [[ -f "$SCRIPT" ]] && (source "$SCRIPT"); then
+    echo "✅ script exists + sources cleanly"
+else
+    echo "❌ script missing or fails to source: $SCRIPT"
+    exit 1
+fi
+# shellcheck disable=SC1091
+source "$SCRIPT"
+
+# numeric_pick: TEMPer external > TEMPer internal > first native/sysfs value
+test_numeric_prefers_external() {
+    if [[ "$(numeric_pick "22.5" "18.2" "" )" == "18.2" ]]; then
+        echo "✅ numeric_pick prefers external probe"
+    else
+        echo "❌ numeric_pick external preference broken"
+        ((++failed))
+    fi
+}
+
+test_numeric_falls_back_internal() {
+    if [[ "$(numeric_pick "22.5" "" "")" == "22.5" ]]; then
+        echo "✅ numeric_pick falls back to internal"
+    else
+        echo "❌ numeric_pick internal fallback broken"
+        ((++failed))
+    fi
+}
+
+test_numeric_uses_first_line_value() {
+    if [[ "$(numeric_pick "" "" "temp1:  +27.5°C (high = +84.0°C)")" == "27.5" ]]; then
+        echo "✅ numeric_pick parses first native temp"
+    else
+        echo "❌ numeric_pick native parse broken: got '$(numeric_pick "" "" "+27.5°C")'"
+        ((++failed))
+    fi
+}
+
+test_numeric_empty_is_error() {
+    if numeric_pick "" "" "" >/dev/null 2>&1; then
+        echo "❌ numeric_pick should fail on no data"
+        ((++failed))
+    else
+        echo "✅ numeric_pick errors on no data"
+    fi
+}
+
+test_numeric_prefers_external
+test_numeric_falls_back_internal
+test_numeric_uses_first_line_value
+test_numeric_empty_is_error
+
+if ((failed > 0)); then
+    echo "❌ $failed numeric-mode test(s) failed"
+    exit 1
+fi
+echo "✅ all numeric-mode tests passed"