Server-only mode & hot reload for faster backend development

[vuon9]

What's this?

Two quality-of-life improvements for backend development:

1. --server-only mode — you can now run just the API server without the desktop app window. No more waiting for Wails to boot when you're only touching backend code.

go run . --server-only              # API on port 8081
go run . --server-only --port 3000  # or any port you like

2. Hot reload with air — change a .go file and the server restarts automatically. No more Ctrl+C / re-run cycles.

task dev:server              # hot reload on 8081
PORT=3000 task dev:server    # hot reload on custom port

Also updated AGENTS.md with a handy reference table for all the common commands (running, testing, linting).

Files touched

• main.go — added --server-only and --port CLI flags
• .air.toml — hot reload config (tracked in git, shared with the team)
• Taskfile.yml — new task dev:server target that auto-installs air
• AGENTS.md — new "Development workflow" section with run/test/lint commands
• docs/superpowers/ — design spec + implementation plan

[github-actions]

Package	Line Rate	Health
devtoolbox/internal/barcode	90%	✔
devtoolbox/internal/codeformatter	75%	➖
devtoolbox/internal/converter	60%	➖
devtoolbox/internal/datagenerator	79%	➖
devtoolbox/internal/datetimeconverter	73%	➖
devtoolbox/internal/jwt	42%	❌
devtoolbox/internal/numberconverter	0%	❌
devtoolbox/internal/settings	0%	❌
Summary	65% (3406 / 5275)	➖

Minimum allowed line rate is 60%