fix: skip diverged forks in drift check + fix 005 patch signature

check-fork-drift.sh: diverged forks (kernel, bootloader, installer)
are intentionally ahead of upstream — skip them to suppress spurious
DRIFT warnings during build preflight.

apply-patches.sh: 005-qtbase patch signature now checks correct path
(recipes/wip/qt/qtbase/recipe.toml) and respects local recipe override.

local/scripts/check-fork-drift.sh

@@ -78,6 +78,12 @@ for fork in "${FORKS[@]}"; do
         continue
     fi
 
+    # Respect diverged mode from fork-upstream-map.toml — these forks are
+    # intentionally ahead of upstream with RB-specific work. Drift is expected.
+    if grep -q "^${fork}[[:space:]]\+.*diverged" "$PROJECT_ROOT/local/fork-upstream-map.toml" 2>/dev/null; then
+        continue
+    fi
+
     # Determine upstream branch (master or main)
     upstream_branch="master"
     if ! (cd "$fork_dir" && git rev-parse --verify upstream/master >/dev/null 2>&1); then