feat: add specialized subagents for manager-mode workflow

[franccesco]

Summary

• Introduces 5 specialized Claude Code subagents tailored to the Bloomy SDK development workflow
• Updates CLAUDE.md with delegation guidelines for manager-mode operation
• Removes generic sdk-product-manager agent in favor of specialized agents

Subagents Added

Subagent	Purpose
api-feature-developer	SDK operations, sync/async implementations, Pydantic models
mkdocs-documentation-writer	MkDocs guides, API docs, README updates
code-quality-reviewer	Quality gates (ruff, pyright, pytest), code review
sdk-test-engineer	Writing tests, pytest fixtures, mocking patterns
version-control-engineer	Git workflows, commits, PRs, releases

Manager Mode

The updated CLAUDE.md promotes a delegation-first approach where Claude:

1. Acts as a coordinator/reviewer rather than direct implementer
2. Chains workflows across subagents (e.g., implement → test → review → commit)
3. Uses parallel agents for independent tasks

Test plan

• Verify subagent files are properly formatted with YAML frontmatter
• Test delegation by asking Claude to implement a new feature
• Confirm workflow chaining works as documented

🤖 Generated with Claude Code