Enhance devcontainer and CI workflows

- Add persistent volume mounts for Go/npm caches (faster rebuilds)
- Add shell config with helpful aliases and custom prompt
- Add comprehensive devcontainer documentation
- Add pre-commit hooks for Go formatting and linting
- Use go-version-file in CI workflows instead of hardcoded versions
- Simplify docker compose commands with --wait flag
- Add gitignore entries for devcontainer auth files

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.devcontainer/.bashrc

@@ -0,0 +1,47 @@
+# Pulse Dev Container Shell Configuration
+
+# Better prompt showing git branch and mock mode
+parse_git_branch() {
+    git branch 2> /dev/null | sed -e '/^[^*]/d' -e 's/* \(.*\)/ (\1)/'
+}
+
+get_mock_status() {
+    if [ -f /workspaces/pulse/mock.env ] && grep -q "PULSE_MOCK_MODE=true" /workspaces/pulse/mock.env 2>/dev/null; then
+        echo " [MOCK]"
+    fi
+}
+
+export PS1='\[\033[01;32m\]\u@pulse-dev\[\033[00m\]:\[\033[01;34m\]\w\[\033[33m\]$(parse_git_branch)\[\033[35m\]$(get_mock_status)\[\033[00m\]\$ '
+
+# Useful aliases
+alias pd='cd /workspaces/pulse && ./scripts/hot-dev.sh'
+alias ptest='go test ./...'
+alias plint='golangci-lint run ./...'
+alias pfmt='gofmt -w -s .'
+alias plog='tail -f /tmp/pulse-dev.log'
+alias mock-on='cd /workspaces/pulse && npm run mock:on'
+alias mock-off='cd /workspaces/pulse && npm run mock:off'
+alias mock-edit='cd /workspaces/pulse && npm run mock:edit'
+
+# Helpful shortcuts
+alias ll='ls -lah'
+alias gs='git status'
+alias gp='git pull'
+alias gc='git commit'
+
+# Show helpful info on shell start
+echo ""
+echo "🚀 Pulse Dev Container"
+echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
+echo "Shortcuts:"
+echo "  pd          - Start hot-reload dev server"
+echo "  ptest       - Run all Go tests"
+echo "  plint       - Run Go linter"
+echo "  pfmt        - Format Go code"
+echo "  plog        - View dev server logs"
+echo "  mock-on/off - Toggle mock mode"
+echo ""
+echo "Debug: Press F5 in VS Code to start debugger"
+echo "Tasks: Cmd+Shift+P → 'Tasks: Run Task'"
+echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
+echo ""