Superset: configura setup, teardown e run dos workspaces

- setup: copia .env, .env.* e CLAUDE.md da raiz (sem sobrescrever) e
  baixa as dependências com cargo fetch --locked. Pode rodar de novo.
- run: guara ui --no-open. A porta padrão é 0, então cada workspace
  recebe uma porta livre do sistema e a URL com o token sai no terminal.
- teardown: encerra o guara ui que ainda esteja vivo neste workspace.
- .gitignore passa a ignorar .env e .env.*.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RRZm8uTVN3WLTwcbrDQAUM

.superset/teardown.sh

@@ -0,0 +1,9 @@
+#!/usr/bin/env bash
+# Runs when a Superset workspace is deleted.
+# Setup starts no background service. The only long-running process is the Run command
+# (`guara ui`), which this workspace builds into its own target/ directory, so stop any
+# copy that is still alive before the worktree is removed.
+set -uo pipefail
+
+pkill -f -- "$PWD/target/.*/guara ui" 2>/dev/null || true
+exit 0