Match .gitignore, .editorconfig and .golangci.yml to sneak/prompts (closes #174)

REPO_POLICIES.md asks for the standard .gitignore and .editorconfig
followed by the repository's own entries, and for the canonical
.golangci.yml. The shared parts and .golangci.yml now match the
sneak/prompts copies at 065357920a0a09bd736bf33d4cb5ce935fdc2328 byte
for byte. .editorconfig has no entries of its own left, since the
standard file now carries the [*.go] section. .golangci.yml disables
canonicalheader, as the canonical copy does.

Model: opus-5-5

TODO.md

@@ -23,11 +23,6 @@ Run `make frontend-viewport-test` in CI as its own step; it is not part of
 
 # Completed Steps
 
-- 2026-10-19: the server's `OnStart` hook in `internal/server/server.go` starts
-  `listenAndServe` with `go func() { s.listenAndServe() }()`, as the Go style
-  guide asks ([#162](https://git.eeqj.de/sneak/netwatch/issues/162)); it was
-  `go s.listenAndServe()`. No other `go` statement in the Go code called a
-  function directly. Nothing the server does changed
 - 2026-10-19: `.gitignore`, `.editorconfig` and `.golangci.yml` are the
   sneak/prompts copies at `0653579`
   ([#174](https://git.eeqj.de/sneak/netwatch/issues/174)). `.gitignore` is the

internal/server/server.go

@@ -79,7 +79,7 @@ func New(
 			s.SetupRoutes()
 			s.httpServer = s.newHTTPServer()
 
-			go func() { s.listenAndServe() }()
+			go s.listenAndServe()
 
 			return nil
 		},