docs: update repo documentation and artifacts

[zhou100]

Summary

• Update README to match the current ChurchMap/FastAPI/React/SQLite stack and active repo commands.
• Add Fly.io deploy workflow, deduplication report, and static design preview artifact.
• Document active env vars, API routes, deployment behavior, and legacy dependency file notes.

Verification

• PASS: npm run build
• FAILING, appears pre-existing and unrelated to this docs/artifacts branch: venv/bin/python -m pytest tests/ -v has 12 failures from schema/auth drift, including missing c.language / reviewer_name columns in test DB setup and tests still expecting anonymous review posts.
• FAILING, appears pre-existing and unrelated to this docs/artifacts branch: npm run lint has 71 existing React prop-types/no-empty/no-unused-vars errors plus 3 warnings.

Notes

This branch started from local uncommitted changes on main, then moved them onto docs/update-readme-and-repo-artifacts so the PR can review them cleanly.
PR includes all current working-tree changes requested: README update, .github/workflows/fly-deploy.yml, dedup_report.csv, and frontend/public/design-preview.html.

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Project	Deployment	Actions	Updated (UTC)
frontend	Error		Apr 14, 2026 4:14am