golangci: run the linters this file claims to configure

[Philip Lombardi (plombardi89)]

Fixes #657.

.golangci.yaml never set linters.default, so it took golangci-lint v2's implicit standard set. Seven linters ran; the rest of the file was inert:

Location	Configured	Status
:35-63	godot, godox, nolintlint, varnamelen settings	linters never ran
:15-24	disable: gocognit, gomoddirectives	already off under standard
:79-84	_test.go exclusion	3 of 4 linters named were off
:99-104	formatters.settings.gci	gci absent from formatters.enable
:6	run.build-tags: int	no //go:build int in the tree

What changed

default: none, every linter named. Listing the five standard linters costs five lines and buys two things: a golangci-lint bump can't change what runs without a diff here, and "every settings block belongs to an enabled linter" becomes checkable by reading the file.

Eighteen linters enabled, each verified at zero findings individually against the pinned v2.13.1: asasalint, asciicheck, bidichk, durationcheck, exptostd, fatcontext, gocheckcompilerdirectives, iface, interfacebloat, loggercheck, misspell, nakedret, nilnesserr, reassign, spancheck, tagalign, testableexamples, whitespace.

decorder also reports zero and is deliberately excluded: every one of its checks defaults to disable-*: true, so enabling it would re-create exactly the problem this PR fixes.

gci enabled. Not cosmetic. goimports sorts within the groups a file already has but never moves an import between them, so the prefix(github.com/Azure/unbounded) section was advisory and first-party imports had settled into the third-party group. Positive control on v2.13.1:

# without gci                          # with gci
import (                               import (
    "context"                              "context"

    inv "github.com/Azure/unbounded/…"     "google.golang.org/grpc"

    "google.golang.org/grpc"               inv "github.com/Azure/unbounded/…"
)                                      )

That accounts for all 21 Go files in this diff. They are imports only, no logic.

./deploy/... added to GO_PACKAGE_PATTERNS. The embed.go files and the render tests guarding the shipped manifests were linted by nothing. They already pass, and the packages load on a fresh clone by design (deploy/machina/embed.go:11-17).

Not in scope

The linters with real findings land separately, per #657. Starting batch is nilerr (14) and predeclared (20), which the issue calls out. nilerr is not all noise: internal/net/controller/site_controller.go:877 treats every lister error as "node was deleted", internal/operator/migrate.go:1666 returns false, nil on err != nil, and internal/net/netlink/link_manager.go:295 treats any LinkByName failure as "doesn't exist". The tree also already carries 5 //nolint:nilerr and 3 //nolint:nilnil directives written against linters that had never run.

Found while doing this, filed separately

make fmt has a latent race. GO_PACKAGE_DIRS contains nested package dirs and gofumpt recurses, so nested files get visited once per ancestor, concurrently. It's masked only because gofumpt currently has nothing to rewrite; an experiment that made it rewrite files hit it immediately:

error: size of hack/cmd/relctl/relctl/version/resolve.go changed during reading
make: *** [Makefile:508: fmt] Error 2

Pre-existing and unrelated to #657, so not fixed here.

Verification

Against the pinned v2.13.1 (Makefile:435), not a locally-installed version — the schema for formatters.settings.gofumpt changed between v2.11 and v2.13, and reading the wrong one sends you the wrong way.

• golangci-lint config verify passes; it did not before.
• make lint clean, make fmt idempotent, go build ./... clean.
• Tests pass for all 21 affected packages.