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/web/misc/markup.go

@@ -14,7 +14,7 @@ import (
 
 // Markup render markup document to HTML
 func Markup(ctx *context.Context) {
-	form := web.GetForm(ctx).(*api.MarkupOption)
+	form := web.GetForm[*api.MarkupOption](ctx)
 	mode := util.Iif(form.Wiki, "wiki", form.Mode) //nolint:staticcheck // form.Wiki is deprecated
 	common.RenderMarkup(ctx.Base, ctx.Repo, mode, form.Text, form.Context, form.FilePath)
 }