fix: remaining npm→pnpm gaps + dockerignore for pnpm symlinks

- container/.dockerignore (new): exclude agent-runner/node_modules and
  agent-runner/dist so COPY agent-runner/ ./ doesn't clobber the
  pnpm-installed node_modules with host directories. Under npm's flat
  layout this was forgiving; under pnpm's symlink layout it's a hard
  conflict (overlay2 cannot copy onto a symlink target).
- setup/{groups,service}.ts: execSync('pnpm run build') not npm.
- setup/index.ts: usage string.
- scripts/*.ts: usage comments + seed-discord final log.
- .claude/settings.json: permission allowlist entries.
- .claude/skills/{add-whatsapp-v2,add-dashboard}/SKILL.md: docs.
- container/skills/{frontend-engineer,vercel-cli,self-customize}/SKILL.md:
  agent-facing docs still told the container agent to run npm.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

container/skills/frontend-engineer/SKILL.md

@@ -66,7 +66,7 @@ Every frontend task follows this sequence. Do not skip steps.
 Run the build and fix ALL errors:
 
 ```bash
-npm run build 2>&1
+pnpm run build 2>&1
 ```
 
 If it fails, **fix it**. Do not deploy broken builds. Do not disable ESLint rules or TypeScript checks to make it pass.
@@ -76,7 +76,7 @@ If it fails, **fix it**. Do not deploy broken builds. Do not disable ESLint rule
 Start the dev server and test in a real browser:
 
 ```bash
-npm run dev &
+pnpm run dev &
 DEV_PID=$!
 sleep 3
 ```