Release v0.29.12

What's Changed

• chore: upgrade pi-ai for Claude Opus 5 by @sarahwooders in #3550
• fix(channels): route shared reload command by @overlord-letta in #3528
• fix(slack): avoid repeated bot thread context by @devanshrj in #3551
• fix(channels): compact persisted channel reminders by @devanshrj in #3552
• fix(slack): enforce loading message limit by @cpacker in #3553
• feat(mcp): add per-agent client-side MCP with OAuth by @letta-integration[bot] in #3549
• fix(mcp): publish reusable client declarations by @letta-integration[bot] in #3557
• chore: bump version to 0.29.12 by @github-actions[bot] in #3558

Full Changelog: v0.29.11...v0.29.12