feat: extend analyze_forces architecture signals

[bntvllnt]

Summary

• extend analyze_forces / forces with shallow, deep, seam, and locality signals
• keep existing output intact while adding new sections for MCP and CLI consumers
• add analyzer tests and docs for the new architecture signals

Changes

• add shallowModules, deepModules, seamCandidates, localityRisks to force analysis types
• compute conservative heuristics in src/analyzer/index.ts
• expose the new fields through src/core/index.ts and CLI forces
• update docs/mcp-tools.md, docs/cli-reference.md, and docs/metrics.md

Validation

• pnpm lint
• pnpm typecheck
• pnpm build
• pnpm test -- src/analyzer/index.test.ts