feat: add SCIM v2 API support (scim-users, scim-groups)

[yamitzky]

Summary

• Slack SCIM v2.0 API のフルサポートを追加（scim-users 5コマンド + scim-groups 5コマンド = 計10コマンド）
• admin.* API では不可能だった org レベルのユーザー無効化（scim-users deactivate）が可能に
• fetch ベースのリソース指向 ScimClient クラスを新設（外部依存なし）
• Agent Skill のレシピ（scim-users.md, scim-groups.md）を追加

New Commands

scim-users

Command	Description
scim-users list	List users (SCIM)
scim-users get	Get user details (SCIM)
scim-users create	Create user (SCIM)
scim-users update	Update user attributes (SCIM)
scim-users deactivate	Deactivate user (SCIM)

scim-groups

Command	Description
scim-groups list	List groups (SCIM)
scim-groups get	Get group details (SCIM)
scim-groups create	Create group (SCIM)
scim-groups update	Update group (SCIM)
scim-groups delete	Delete group (SCIM)

Test plan

• 全149テスト pass（SCIM 関連 31テスト追加）
• bun run lint (tsc --noEmit) pass
• scim-users list --count 5 で実際の Enterprise Grid org に対して動作確認済み

🤖 Generated with Claude Code

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Note

High Risk
Adds new org-level user/group mutation commands (including user deactivation) and a new HTTP client path, so incorrect parameters or bugs could impact real Slack identities at scale.

Overview
Adds Slack SCIM v2.0 API support via a new fetch-based ScimClient (src/scim-client.ts) with typed models (src/scim-types.ts) and error handling.

Introduces 10 new CLI commands under scim-users and scim-groups (list/get/create/update + deactivate/delete) and wires them into src/index.ts (parser + routing + output formatting).

Adds comprehensive unit tests for the SCIM client and commands, and updates docs/skill recipes (README*, CLAUDE.md, skills/.../SKILL.md, new SCIM recipe files) plus SCIM design/implementation plan documents under docs/superpowers/.

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