v2026.5.11171007

Changes:

• #494: Update release agent with explicit dev bump PR steps
• #493: Bump version to 2026.5.0-dev
• #492: Add manual validation stage to stable release pipeline
• #491: Switch stable pipeline trigger to release branches only
• #490: Narrow stable pipeline tag trigger to v* pattern
• #489: Bump version to 2026.4.0
• #488: Add release agent instructions

This list of changes was auto generated.