chore: phase branching + graphify auto_update; ignore graph build-status and tmp scratch

.gitignore

@@ -49,4 +49,8 @@ graphify-out/
 # Intel / graph diff baselines (local-only; regenerated on each refresh/build)
 .planning/intel/.last-refresh.json
 .planning/graphs/.last-build-snapshot.json
+.planning/graphs/.last-build-status.json
 .planning/research/.cache/
+
+# Transient workflow scratch
+.planning/tmp/

.planning/config.json

@@ -7,7 +7,7 @@
   "firecrawl": false,
   "exa_search": false,
   "git": {
-    "branching_strategy": "milestone",
+    "branching_strategy": "phase",
     "create_tag": true,
     "phase_branch_template": "gsd/phase-{phase}-{slug}",
     "milestone_branch_template": "gsd/{milestone}-{slug}",
@@ -90,6 +90,7 @@
     "enabled": true
   },
   "graphify": {
-    "enabled": true
+    "enabled": true,
+    "auto_update": true
   }
 }