Improve external authority signals for EloqKV

[liunyl]

Epic: #47

Background

Search and AI visibility depend on trustworthy external signals as well as on-site content. EloqKV should have consistent positioning across GitHub and external database/community surfaces.

Tasks

• Update EloqKV GitHub README opening definition and links to product/benchmark/cost pages.
• Add or request relevant GitHub topics: redis-compatible, redis-alternative, key-value-store, nvme, distributed-database, acid-transactions.
• Prepare DB-Engines submission checklist.
• Prepare ethical community distribution plan for Hacker News, Reddit, newsletters, and technical communities.
• Define Stack Overflow guidelines: answer only real questions, disclose affiliation, avoid promotional answers.

Acceptance criteria

• GitHub README matches website positioning.
• External distribution checklist exists and avoids spammy promotion.
• DB-Engines submission requirements are documented.