Replace 7YA operating brief with 7ya.io operational command plan and add implementation checklist

[vepretski]

Motivation

• Consolidate and refocus the previous high-level 7YA brief into an operational playbook for 7ya.io as a production civic-intake system.
• Provide clear, actionable steps to get a controlled intake live within 72 hours while enforcing privacy, legal, and operational guardrails.
• Supply a concrete checklist to guide implementation and handoff between ops, data, privacy, community, and escalation owners.

Description

• Replaced the original 7ya-command-center.md content with a new 7ya.io Command Center document that defines three linked tracks: platform reliability, civic intake operations, and audience/trust growth.
• Added a detailed 72-Hour Plan covering platform hardening, controlled data intake, first operational brief, and the recurring operating cycle.
• Introduced a Minimum Data Contract enumerating required fields and a strict list of data items that must never be collected, along with non-negotiable operating rules, an ownership matrix, weekly KPIs, a public update template, and escalation triggers.
• Added a new implementation checklist at input/7ya-implementation-checklist.md that maps the plan into actionable verification items across platform reliability, intake product, privacy/compliance, daily operations, communications, evidence brief, and exit criteria.

Testing

• No automated tests were executed because this change is documentation-only and contains operational checklists and procedures.

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Codex Task