Update renovate and pinning behavior, run tools from go.mod (#4759)

- Renovate

config:recommended (config:base is deprecated) and matchPackageNames globs instead of the deprecated matchPackagePrefixes.
Vulnerability alerts get a fast path: 2-day quarantine, no concurrency/hourly/schedule limits.
Go modules are no longer grouped into one "go deps" PR — each gets its own, so a bad bump can be reverted alone. The pion modules stay grouped as a documented exception: they're co-released and interdependent, so individual PRs wouldn't build.
First-party github.com/livekit/** skips the 2-week quarantine.
go.mod's go directive is no longer an update target — the build toolchain is pinned in the Dockerfile instead.
Dockerfile deps get pinDigests; the golang image is ungrouped with separateMinorPatch so a patch and a minor bump are each separately approvable.
Custom manager to bump the builder image's -alpineA.B suffix together with its digest, which the stock docker manager holds fixed.

- Pinning

Both Dockerfiles pin golang and alpine by digest alongside the readable tag.
GOTOOLCHAIN=local so a go.mod bump fails loudly instead of silently downloading a different toolchain.
apk upgrade in the runtime stage — a digest pin plus the 2-week quarantine would otherwise ship base-package CVEs Alpine has already fixed. This relies on a cold layer cache, which holds today because the release workflow configures no buildx cache; there's a comment saying so.
Workflows resolve the Go version from the Dockerfile via .github/scripts/go-version.sh, so tests, releases and images share one toolchain.

- Tools

All four code generators now come from the module graph, and tools/tools.go (the pre-Go-1.24 blank-import idiom) is replaced by go.mod tool directives:

tool	how	why
goimports	go tool	lives in x/tools — its own module is the one being selected
gotestfmt	go tool	zero dependencies, nothing to skew
wire	go run	pins x/tools v0.24.1; building it in our graph changes its output
counterfeiter	go run	unchanged, matches its //go:generate directives

The wire distinction is load-bearing. Building wire inside our module raises it from the x/tools v0.24.1 it pins to our v0.48.0, and that module version difference changes what it generates: it falls back to v/v2/v3 instead of deriving real identifiers from the type. wire_gen.go is regenerated here to match the in-module build — a cosmetic rename of 9 lines, with no other change to the generated code.

golangci-lint deliberately keeps its action rather than becoming a tool: it pins its own x/tools (v0.44.0 vs our v0.48.0) for the analyzers it bundles, adding it to go.mod would double our go.mod/go.sum (158→338 / 441→889 lines), and the action supplies caching, only-new-issues and PR annotations that invoking a binary can't. Its version stays manual by request.

.github/workflows/docker.yaml

@@ -43,19 +43,28 @@ jobs:
             type=semver,pattern=v{{version}}
             type=semver,pattern=v{{major}}.{{minor}}
 
+      # Generate with the same Go toolchain the published image is built with
+      - name: Resolve Go version
+        id: go-version
+        run: |
+          # Assign first so a failed lookup trips `set -e`; inside echo its exit
+          # status would be discarded and an empty version written.
+          version=$(.github/scripts/go-version.sh Dockerfile)
+          echo "version=$version" >> "$GITHUB_OUTPUT"
+
       - name: Set up Go
         uses: actions/setup-go@b7ad1dad31e06c5925ef5d2fc7ad053ef454303e # v7
         with:
-          go-version-file: "go.mod"
+          go-version: ${{ steps.go-version.outputs.version }}
 
       - name: Download Go modules
         run: go mod download
 
+      # Run mage at the version go.mod pins, rather than the mage-action's
+      # `version: latest`, so the binary matches the mage/mg library the magefile is
+      # compiled against and Renovate owns the version like any other module.
       - name: Generate code
-        uses: magefile/mage-action@a662bd8c29d8106879588cfff83b2faf6e6f59db # v4
-        with:
-          version: latest
-          args: generate
+        run: go run github.com/magefile/mage generate
 
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@4d04d5d9486b7bd6fa91e7baf45bbb4f8b9deedd # v4