fix(mcp): use package version in server metadata

[epowell40]

Summary

• read the MCP server version from packages/mcp/package.json instead of hard-coding 0.1.0
• keep a 1.2.0 fallback so server metadata stays aligned with the published package

Fixes #152.

Test

• corepack pnpm install --filter @betterdb/mcp --ignore-scripts
• corepack pnpm --filter @betterdb/mcp build

Note: full workspace install attempted first but the Windows environment is missing the ClangCL build toolset required by hnswlib-node.

[github-actions]

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[epowell40]

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