ci: migrate Nix CI to official installer and hestia cache

Swap nix-quick-install-action -> nix-installer-action and
cache-nix-action -> Mic92/hestia/action across every Nix workflow, drop
the now-unneeded cache keys, and run devShell tooling through a
defaults.run.shell. Add gc.yml to trim the hestia cache daily.

.github/workflows/release.yml

@@ -7,6 +7,10 @@ on:
       - "*" # triggers only if push new tag version
   workflow_dispatch:
 
+defaults:
+  run:
+    shell: nix develop --fallback --command bash -e {0}
+
 jobs:
   goreleaser:
     if: github.repository == 'juanfont/headscale'
@@ -30,14 +34,10 @@ jobs:
           username: ${{ github.repository_owner }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
-      - uses: nixbuild/nix-quick-install-action@2c9db80fb984ceb1bcaa77cdda3fdf8cfba92035 # v34
-      - uses: nix-community/cache-nix-action@135667ec418502fa5a3598af6fb9eb733888ce6a # v6.1.3
-        with:
-          primary-key: nix-${{ runner.os }}-${{ runner.arch }}-${{ hashFiles('**/*.nix',
-            '**/flake.lock') }}
-          restore-prefixes-first-match: nix-${{ runner.os }}-${{ runner.arch }}
+      - uses: NixOS/nix-installer-action@6b8548fe06acfb0155a50ab5d561accb215764cc # main
+      - uses: Mic92/hestia/action@ff07bb902a9968ac0c3d0e51d90a606662a375d8 # main
 
       - name: Run goreleaser
-        run: nix develop --fallback --command -- goreleaser release --clean
+        run: goreleaser release --clean
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}