[Plugin Pack Child] Next Wave Backlog Spec & Sequencing

[ashleyshaw]

Child of #732. Define backlog sequencing and readiness for next-wave plugin pack tasks, including dependency and risk mapping.

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Definition of Ready (DoR)

• Task described and scoped
• Estimate added if relevant

Definition of Done (DoD)

• Task completed and documented
• Changelog entry prepared for PR
• PR uses correct branch prefix

[linear-code]

LS-875