Add Ruby gRPC and Falcon matcher coverage

[zilbonn]

Summary

• Fixes Matcher coverage: Falcon + async-grpc Ruby services (no web framework gate fires) #87
• Add Ruby gRPC / async-grpc, Falcon/Rack, and async-websocket matcher coverage for full-repo scans
• Emit Ruby-specific tech tags and shared grpc only to activate the existing proto wire-surface matcher
• Add .ru language plumbing, prompt highlights, slug notes, docs, and regression coverage

Validation

• npx pnpm@8.15.9 exec vitest run --project scanner packages/scanner/src/__tests__/detect-tech.test.ts packages/scanner/src/__tests__/framework-matchers.test.ts packages/scanner/src/__tests__/ruby-async-scan.test.ts --project processor packages/processor/src/__tests__/prompt-assemble.test.ts
• UPDATE_PROMPT_SAMPLES=1 npx pnpm@8.15.9 test:unit
• npx pnpm@8.15.9 lint
• npx pnpm@8.15.9 -r build
• git diff --check

[vercel]

@JacobDiamond-Jane is attempting to deploy a commit to the Vercel Labs Team on Vercel.

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[zilbonn]

This is ready for review. The latest commit is signed and verified, local validation passed, and the remaining Vercel deploy check appears to need maintainer approval.