feat(templates): add SDR Agent sample template

[Schlaflied]

Description

Add a new SDR Agent sample template — a 6-node AI pipeline that automates sales development outreach: score contacts by priority, filter suspicious profiles, generate personalized messages, and create Gmail drafts for human review.

Type of Change

• New feature (non-breaking change that adds functionality)

Related Issues

Closes #5177

Changes Made

New directory examples/templates/sdr_agent/ with 9 files:

• agent.json, agent.py, nodes/__init__.py, config.py, tools.py, __init__.py, __main__.py, mcp_servers.json, README.md

Pipeline: Intake → Score Contacts → Filter Contacts → Personalize → Send Outreach → Report

Key safety constraints:

• Never sends emails — only creates Gmail drafts for human review
• Skips contacts with risk_score >= 7 (scam detection)
• Respects max_contacts batch limit

Testing

• Lint passes (uv run ruff check examples/templates/sdr_agent/ → All checks passed!)
• Manual testing performed — uv run python -m examples.templates.sdr_agent validate → Agent is valid

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings