mm scripts: default to MiniMax-M3.1-Flash-Preview with per-script effort

Flash is the default model; --m3 falls back to M3, --effort overrides.
Defaults: max (review-minimax, review-loop, mm-worktree-task), medium
(explore), low (ci-triage). ask-minimax-run applies MINIMAX_EFFORT to
Flash models when --effort is not passed. Bump stale fixture date.

scripts/ask-minimax-run

@@ -26,4 +26,15 @@ export CLAUDE_CONFIG_DIR="$MINIMAX_DIR"
 export CLAUDE_CODE_DISABLE_ADAPTIVE_THINKING=1
 export COLORTERM=truecolor
 
+# MINIMAX_EFFORT (provider.env) applies to Flash models only, unless the caller passed --effort.
+model="${ANTHROPIC_MODEL:-}"; has_effort=0; prev=""
+for a in "$@"; do
+    [[ "$prev" == "--model" ]] && model="$a"
+    [[ "$a" == "--effort" ]] && has_effort=1
+    prev="$a"
+done
+if [[ -n "${MINIMAX_EFFORT:-}" && $has_effort -eq 0 && "$model" == *Flash* ]]; then
+    set -- --effort "$MINIMAX_EFFORT" "$@"
+fi
+
 exec claude "$@"