AGENTS, README, flake: drop unused golines

.golangci.yaml never enabled golines and lll is off; Go formatting is
gofumpt, gci and goimports. Remove golines from the dev shell too.

AGENTS.md

@@ -310,8 +310,9 @@ a broken one.
 - **Protobuf regeneration**: changes under `proto/` require
   `make generate` (which runs `buf generate`) and should land in a
   **separate commit** from the callers that use the regenerated types.
-- **Formatting** is enforced by `golangci-lint` with `golines` (width 88)
-  and `gofumpt`. Run `make fmt` or rely on the pre-commit hook.
+- **Formatting** is enforced by the `golangci-lint` formatters in
+  `.golangci.yaml` (`gofumpt`, `gci`, `goimports`). No line-length limit is
+  enforced. Run `make fmt` or rely on the pre-commit hook.
 - **Logging** uses `zerolog`. Prefer single-line chains
   (`log.Info().Str(...).Msg(...)`). For 4+ fields or conditional fields,
   build incrementally and **reassign** the event variable:

README.md

@@ -107,8 +107,8 @@ To ensure we have some consistency with a growing number of contributions,
 this project has adopted linting and style/formatting rules:
 
 The **Go** code is linted with [`golangci-lint`](https://golangci-lint.run) and
-formatted with [`golines`](https://github.com/segmentio/golines) (width 88) and
-[`gofumpt`](https://github.com/mvdan/gofumpt).
+formatted with the `golangci-lint` formatters
+([`gofumpt`](https://github.com/mvdan/gofumpt), `gci`, `goimports`).
 Please configure your editor to run the tools while developing and make sure to
 run `make lint` and `make fmt` before committing any code.
 

flake.nix

@@ -86,10 +86,6 @@
             buildGoModule = buildGo;
           };
 
-          golines = prev.golines.override {
-            buildGoModule = buildGo;
-          };
-
           # goimports and friends: they parse Go with the parser of the Go
           # they were built with, so an older one rejects new syntax.
           gotools = prev.gotools.override {
@@ -123,7 +119,6 @@
           ++ [
             golangci-lint
             golangci-lint-langserver
-            golines
             prettier
             nixfmt
             goreleaser
@@ -217,12 +212,12 @@
             }
           );
 
-          # Full-tree golangci-lint (golines, gofumpt, etc.); uses the overlay's
+          # Full-tree golangci-lint (gofumpt, gci, etc.); uses the overlay's
           # golangci-lint built against the pinned Go.
           golangci-lint = fc.goLint common;
 
           # nixfmt + prettier, excluding generated output. goFmt = "off":
-          # Go formatting (golines, gofumpt) is enforced by the golangci-lint
+          # Go formatting (gofumpt, gci) is enforced by the golangci-lint
           # check, not treefmt. prettierExts matches the old prettier-lint glob
           # (no json: testdata fixtures are hand-formatted).
           formatting = fc.goFormat (