GitHub Enterprise support via configurable API base URL

[devblac]

GitHub Enterprise support via configurable API base URL

Context

I tried pointing prw at a GitHub Enterprise host and realized the client is hardwired to https://api.github.com, so nothing worked.
 

Problem

NewClient ignores any host override; config/CLI don’t expose an API base URL, so requests always go to GitHub.com.
 

Expected behavior

I can set an API base URL via config, with an optional PRW_API_BASE_URL env var override that defaults to https://api.github.com, and the client uses it for all requests after basic validation.
 

Scope / non-goals

• No fancy host auto-discovery.
• Keep defaults unchanged for GitHub.com users.
• Only add the minimal validation to avoid malformed URLs.
   

Acceptance criteria

• Config gains an api_base_url option with default https://api.github.com.
• CLI wiring passes the configured base URL into github.NewClient.
• NewClient validates and uses the provided base URL for requests.
• README includes a short “GitHub Enterprise” setup note.
• Tests cover loading a custom host and verifying requests target it.
• Support PRW_API_BASE_URL env var overriding config
   

Hints

Touch internal/config/config.go, cmd/prw/main.go, and internal/github/client.go.