refactor(deps): migrate from nektos/act fork to gitea/runner (#37557)

Migrate to https://gitea.com/gitea/runner/releases/tag/v1.0.0 which
includes the `act` package directory previously referenced by
`nektos/act`.

Signed-off-by: silverwind <me@silverwind.io>
Co-authored-by: Claude (Opus 4.7) <noreply@anthropic.com>
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

go.mod

@@ -12,6 +12,7 @@ require (
 	code.gitea.io/sdk/gitea v0.24.1
 	codeberg.org/gusted/mcaptcha v0.0.0-20220723083913-4f3072e1d570
 	connectrpc.com/connect v1.19.2
+	gitea.com/gitea/runner v1.0.0
 	gitea.com/go-chi/binding v0.0.0-20260414111559-654cea7ac60a
 	gitea.com/go-chi/cache v0.2.1
 	gitea.com/go-chi/captcha v0.0.0-20240315150714-fb487f629098
@@ -85,7 +86,6 @@ require (
 	github.com/microsoft/go-mssqldb v1.9.6
 	github.com/minio/minio-go/v7 v7.1.0
 	github.com/msteinert/pam/v2 v2.1.0
-	github.com/nektos/act v0.2.63
 	github.com/niklasfasching/go-org v1.9.1
 	github.com/opencontainers/go-digest v1.0.0
 	github.com/opencontainers/image-spec v1.1.1
@@ -301,8 +301,6 @@ ignore (
 
 replace github.com/jaytaylor/html2text => github.com/Necoro/html2text v0.0.0-20250804200300-7bf1ce1c7347 // jaytaylor/html2text is unmaintained
 
-replace github.com/nektos/act => gitea.com/gitea/act v0.261.10 // gitea maintains its own package
-
 replace github.com/urfave/cli/v3 => github.com/urfave/cli/v3 v3.4.1 // v3.6.2 breaks -c flag parsing in help commands
 
 replace go.yaml.in/yaml/v4 => go.yaml.in/yaml/v4 v4.0.0-rc.3 // rc.4 changes block scalar serialization, wait for stable release