P2: Add 'Who's Using GoSQLX' section to README and activate GitHub Discussions

[ajitpratap0]

Problem

GoSQLX has no social proof in the README. Enterprise evaluators and new visitors see a technically excellent project but no evidence of real-world usage. For infrastructure libraries, a 'Who's Using This' section is the primary trust signal after star count.

Why This Matters

• The clone/view ratio (595 unique cloners in 14 days) proves people are trying the library
• Zero of these are visible in the README
• Competitors like vitess and pg_query_go have extensive 'used by' sections
• Even 3 entries (including personal projects) change first impressions significantly

Actions

README Section (immediate)

Add after the badges section:

## Who's Using GoSQLX

| Project | Use Case |
|---------|----------|
| [GoSQLX Playground](https://gosqlx.dev/playground) | Interactive WASM SQL analysis |
| [GoSQLX MCP Server](https://mcp.gosqlx.dev) | AI-assisted SQL tooling |
| [GoSQLX VS Code Extension](https://marketplace.visualstudio.com/items?itemName=ajitpratap0.gosqlx) | IDE SQL intelligence |

*Using GoSQLX in production? [Add your project](https://github.com/ajitpratap0/GoSQLX/discussions)*

GitHub Discussions Activation

• Enable GitHub Discussions on the repo (Settings → General → Features → Discussions)
• Create pinned Discussion: "Show and Tell — What are you building with GoSQLX?"
• Create pinned Discussion: "Q&A — Ask anything about GoSQLX"
• Create category: "Show and Tell", "Q&A", "Ideas", "Announcements"
• Link from README Contributing section

Outreach

• DM or email the 595 unique cloners (not possible via GitHub) — instead, add a "how is your evaluation going?" note in the README's Getting Started section
• Add a brief survey link (GitHub Discussions question) asking: what are you building?

Acceptance Criteria

• README has 'Who's Using GoSQLX' section with at least 3 entries
• GitHub Discussions enabled with 4 categories
• 2 pinned discussions created (Show and Tell, Q&A)
• README Contributing section links to Discussions
• CONTRIBUTING.md updated with Discussions link