Add E-Signature Feature to React/Node TypeScript App

We have a working full-stack Credit Card Validator app and need an experienced developer to add e-signature capture (draw/type on screen, submit via API). This is not cryptographic PDF signing or DocuSign integration.

Existing stack (already built):

Frontend: React, TypeScript, Vite, CSS Modules, custom fintech UI (blue theme, responsive, accessible)
Backend: Node.js, Express, TypeScript with clean architecture (routes, controllers, services, validators, middleware)
Monorepo: npm workspaces
Testing: Vitest (backend unit/integration + frontend component tests)
Deployment: Docker Compose ready
What you will build:

Signature UI

Canvas signature pad (mouse + touch)
Optional typed signature mode
Clear, undo, and basic validation (e.g. reject empty signature)
Integrate into existing page layout and styling
API integration

New backend endpoint(s), e.g. POST /api/signature
Request: signature data (base64 PNG/SVG), optional signer name
Response: success payload with signature ID/URL, timestamp, and metadata
Proper HTTP status codes, input validation, and error handling
Backend logic

Follow existing project structure (controller → validator → service)
Validate payload size/format
Return signature as PNG or SVG + metadata (timestamp, optional signer name)
No database required unless you propose file storage and we agree
UI/UX

Match current fintech/healthcare aesthetic (rounded corners, soft shadows, blue theme)
Mobile-friendly and keyboard accessible
Visible focus states and screen-reader friendly labels
Testing

Backend: unit tests for validation/service logic + API integration tests
Frontend: component tests + user interaction tests (draw, clear, submit)
All existing tests must continue to pass
Documentation

Update README with new API contract, setup notes, and any new env vars
Requirements:

Strong experience with React, Node.js, and TypeScript
Experience with canvas signature libraries (signature_pad, react-signature-canvas, or similar)
Solid understanding of REST APIs and clean code practices
Ability to write meaningful tests, not just happy-path coverage
Good communication and ability to work from an existing codebase
Deliverables:

Feature implemented in our private GitHub repo (via PR or agreed branch)
Working local setup (npm install → npm run dev → feature works)
Brief summary of your approach, libraries chosen, and trade-offs
List of any new environment variables or config changes
To apply: Type "E-Signature" at the top of your proposal and include:

Links to similar work (signature/canvas/form projects)
Your proposed approach and library choice
Estimated timeline and fixed-price quote
Any questions about scope before starting
Repo access will be granted after we shortlist and agree on terms.