release: FixMap v0.7.4

[aryamthecodebreaker]

Summary

• fixes every open 0.7.3 report across ranking, CLI, MCP, GitHub Action, verification, diagnostics, and the web demo
• releases all package and registry metadata as 0.7.4 and refreshes README, changelog, benchmark evidence, and launch copy
• adds regression coverage for every reported failure, including a real MCP plan → edit → verify round trip

Verification

• npm run ci — 234 tests, typecheck, lint, production builds, Action bundle/metadata, server manifest, smoke, regression evaluation, and scanner benchmark
• npm audit --omit=dev --audit-level=high — 0 vulnerabilities
• held-out gate — 7/12 Top-1, 9/12 Top-3/5
• development regression gate — 10/15 Top-1, 15/15 Top-3/5
• adversarial gate — 8/8, zero false-confidence cases
• npm pack dry-runs for @aryam/fixmap-core@0.7.4 and @aryam/fixmap@0.7.4

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