Refresh CouncilLogic brand and public framing

[apcar]

What changed

• Replaces the fixed-member square artwork with a provider-count-neutral CouncilLogic mark, a 256px icon, and a 1520×400 README header matching PageParcel's public presentation footprint.
• Reframes the README around configurable heterogeneous-model deliberation while keeping the current five-provider, eleven-call default explicit.
• Updates public-facing CouncilLogic naming and repository links across citation, support, licensing, security, and contributor surfaces.
• Corrects operations guidance for five-provider quorum tolerance and configurable provider rosters.

Why

The previous radial graphic visibly encoded four council members, so it became inaccurate when Grok joined and would fail again as the roster changed. The product identity should describe the governed process, not freeze a provider count.

User impact

The repository landing page is now visually aligned with PageParcel and remains accurate as providers are added or removed. Runtime compatibility identifiers such as model-council, model_council, and MODEL_COUNCIL_* remain unchanged.

Validation

• 101 unit tests passed.
• Python source, tests, and scripts compiled successfully.
• Both SVGs passed XML validation and rendered successfully.
• git diff --cached --check passed.
• Staged-tree secret scan found no API-key-shaped values.
• Two independent patch reviews found no remaining artifact-quality or correctness blocker.