Add Taskfile, update README and CLAUDE.md with dev instructions

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -4,27 +4,21 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 
 ## Commands
 
-### Backend (Go)
+A `Taskfile.yml` is provided — run `task` to list all tasks. Key ones:
+
 ```bash
-go build ./...                    # Build all packages
-go run ./cmd/server               # Run the server (requires web/build/ to exist)
-go test ./...                     # Run all tests
-go test ./internal/volunteer/...  # Run tests for a single package
+task build          # build frontend + Go binary
+task go:run         # build frontend then start server on :8080
+task web:dev        # frontend hot-reload dev server on :3000
+task go:test        # run all Go tests
+task go:test:verbose
+task go:lint        # go vet
+task web:test       # frontend tests
+task docker:up      # docker-compose up --build
+task clean          # remove build artifacts
 ```
 
-### Frontend (React / CRA)
-```bash
-cd web
-npm install       # Install dependencies
-npm run build     # Production build → web/build/
-npm start         # Dev server on :3000 (proxies /api/v1 to :8080)
-npm test          # Run tests
-```
-
-### Docker
-```bash
-docker-compose up --build   # Build and run the full stack
-```
+For a single Go package test: `go test ./internal/volunteer/...`
 
 ## Architecture