roadmap(pillar 7): metagraphed ecosystem integration

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Goal: wire gittensory (depth: contribute code to gittensor SN74) to its sibling metagraphed (breadth: discover/health/how-to-call for EVERY Bittensor subnet — https://metagraph.sh). Funnel + data-validation; keep scopes distinct (link, don't merge).

Sub-issues:

• discovery funnel: list gittensory as SN74's contribution interface in metagraphed #695 — discovery funnel: list gittensory as SN74's contribution interface in metagraphed
• cross-MCP related-tools hints (gittensory ↔ metagraphed) #696 — cross-MCP related-tools hints
• gittensory consumes metagraphed: validate subnet/netuid claims as gate evidence #697 — gittensory validates subnet/netuid claims via metagraphed (gate evidence)
• shared brand / cross-promo footer (gittensory ↔ metagraphed) #698 — shared brand / cross-promo footer

Done when: an agent discovering gittensor via metagraphed is routed to gittensory, and gittensory can validate subnet claims via metagraphed.

Part of #525.