feat: add local development configuration workflow (Closes #32)

[panditdhamdhere]

Summary

• Adds typed local-development helpers (resolveLocalConfig, createLocalClient, checkLocalNetwork) with defaults, injected env loading, required contract ID, and loopback / host.docker.internal enforcement for plain http:// RPC URLs.
• Adds optional Quickstart support via docker-compose.local.yml (npm run local:up / local:down), .env.example, and .gitignore entries for .env.
• Documents the workflow, edge cases, security assumptions, and compliance disclaimer in docs/local-development.md, with links from README / environments / CONTRIBUTING / API reference.

Behaviour notes for reviewers

• createLocalClient / resolveLocalConfig reject remote http:// RPC hosts unless allowNonLoopbackRpc: true.
• Bare new AegisClient({ environment: 'local', ... }) is unchanged; local workflow hardening lives in the new helpers.
• checkLocalNetwork maps refused local connections to unavailable with a start-Docker hint (not retry-with-backoff).

Test plan

• npm run check (build + unit tests + compat)
• tests/local-config.test.ts covers precedence, rejection matrix, secret non-echo, and readiness-unavailable
• Skim docs/local-development.md reviewer checklist

Closes #32