Revert "fix: disable virtual extmarks for file/agent mentions (#4731)"

This reverts commit 673dbeee09d30c32bf4a6c93a96cfa7bb147dfa1.

packages/opencode/src/cli/cmd/tui/component/prompt/autocomplete.tsx

@@ -81,6 +81,7 @@ export function Autocomplete(props: {
     const extmarkId = input.extmarks.create({
       start: extmarkStart,
       end: extmarkEnd,
+      virtual: true,
       styleId,
       typeId: props.promptPartTypeId(),
     })

packages/opencode/src/cli/cmd/tui/component/prompt/index.tsx

@@ -310,6 +310,7 @@ export function Prompt(props: PromptProps) {
         const extmarkId = input.extmarks.create({
           start,
           end,
+          virtual: true,
           styleId,
           typeId: promptPartTypeId,
         })