fix: keep new agent bootstrap in user scope

[Eilen6316]

Summary

• avoid pre-creating an empty custom agent before the bootstrap flow saves it
• pass agent_name with the initial bootstrap message so setup_agent writes the named agent
• stamp the authenticated user_id into run context and have setup_agent prefer it for user-scoped persistence

Closes #2782

Tests

• uv run pytest tests/test_setup_agent_tool.py tests/test_gateway_services.py -q
• uv run ruff check app/gateway/services.py packages/harness/deerflow/tools/builtins/setup_agent_tool.py tests/test_gateway_services.py tests/test_setup_agent_tool.py
• pnpm exec tsc --noEmit

[Copilot]

Pull request overview

This PR fixes the “New Agent” bootstrap flow so that a named custom agent is only persisted after the bootstrap/save sequence completes, and it is always persisted under the authenticated user’s scope (not the default user bucket).

Changes:

• Frontend no longer pre-creates an empty custom agent; instead it passes agent_name in the initial bootstrap message context.
• Gateway stamps the authenticated user_id into the run context so background tool execution can reliably persist user-scoped files.
• setup_agent now prefers runtime.context["user_id"] (when present) to avoid falling back to default when ContextVars aren’t available.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
frontend/src/core/i18n/locales/zh-CN.ts	Updates bootstrap copy to instruct designing SOUL.md before saving.
frontend/src/core/i18n/locales/en-US.ts	Updates bootstrap copy to reflect the revised save-first flow.
frontend/src/app/workspace/agents/new/page.tsx	Removes empty-agent pre-creation and forwards agent_name via message context.
backend/tests/test_setup_agent_tool.py	Adds regression coverage ensuring runtime user_id is used when ContextVar user is missing.
backend/tests/test_gateway_services.py	Adds test ensuring authenticated user_id overrides any client-supplied user_id in run context.
backend/packages/harness/deerflow/tools/builtins/setup_agent_tool.py	Uses runtime context user_id for user-scoped agent persistence.
backend/app/gateway/services.py	Injects authenticated user_id into run context before background execution.