chore: enable forcetypeassert linter, fix issues (#38804)

Enable [`forcetypeassert`](https://github.com/gostaticanalysis/forcetypeassert)
linter to prevent unchecked type assertions. ~650 issues fixed, most
fixes were clean, some use `setting.PanicInDevOrTesting`.

The only behaviour changes are where code would previously send a 500 error
or panic, a 4xx error is now emitted.

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

routers/api/actions/artifacts.go

@@ -75,6 +75,7 @@ import (
 	"gitea.dev/modules/json"
 	"gitea.dev/modules/log"
 	"gitea.dev/modules/optional"
+	"gitea.dev/modules/reqctx"
 	"gitea.dev/modules/setting"
 	"gitea.dev/modules/storage"
 	"gitea.dev/modules/util"
@@ -98,7 +99,7 @@ type ArtifactContext struct {
 
 func init() {
 	web.RegisterResponseStatusProvider[*ArtifactContext](func(req *http.Request) web_types.ResponseStatusProvider {
-		return req.Context().Value(artifactContextKey).(*ArtifactContext)
+		return reqctx.MustContextValue[*ArtifactContext](req.Context(), artifactContextKey)
 	})
 }