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.

specs/mm-worktree-task.spec.md

@@ -26,6 +26,8 @@ mm-worktree-task <item-uuid> [OPTIONS]
 | `--docs all\|recent\|none` | `recent` | Which item documents to bundle. `recent` = documents updated in the last 14 days; falls back to `all` if the CLI does not expose update dates. The full list of document names is always included in the prompt regardless of which are bundled. |
 | `--tools "<list>"` | — | Extra `--allowedTools` entries merged into the default allowlist (comma-separated). |
 | `--timeout <secs>` | `1800` | Max seconds the sub-session may run (`timeout <secs>` wrapper). |
+| `--m3` | off | Use `MiniMax-M3[1m]` instead of the default `MiniMax-M3.1-Flash-Preview` (1M window natively, always thinks). No effort is sent unless `--effort` is given. |
+| `--effort <level>` | `max` | Thinking depth `low\|medium\|high\|xhigh\|max`, passed to `ask-minimax-run --effort`. Any other value exits 1. |
 | `--gate "<command>"` | — | Supervisor gate: after the sub-session exits, `mm-worktree-task` itself re-runs this command in the worktree against the sub-session's LAST commit and appends a `## Supervisor gate` section to the result file (see Behaviour §8). Never trust the agent's own "tests pass" claim — this re-run is the check. |
 | `--gate-timeout <secs>` | `900` | Max seconds `--gate`'s command may run before it is killed and recorded as a timed-out (failed) gate. |
 | `--context <name>` | resolved (see §0) | `cp-cli --context` used for every planner call. |
@@ -76,7 +78,7 @@ mm-worktree-task <item-uuid> [OPTIONS]
    - If `--brief <file>` is given, its content is appended (or used standalone as the task body when no uuid was given).
 8. Launch detached (skipped under `--dryrun` and `--collect`):
    ```
-   cd <worktree> && setsid nohup timeout <secs> ask-minimax-run --model "MiniMax-M3[1m]" \
+   cd <worktree> && setsid nohup timeout <secs> ask-minimax-run --model "$MODEL" --effort "$EFFORT" \
      --allowedTools "<default-allowlist>[,<--tools>]" --permission-mode acceptEdits \
      --add-dir <report-dir> -p "$(cat <prompt-file>)" \
      > <report-dir>/<slug>-stdout.txt 2>&1