Enable git attribution across Codex entry points (#34819)

## What changed

- Install the git attribution extension in the app server, MCP server, and `codex debug prompt-input` so authenticated workspace policy controls the commit and pull request attribution instructions sent to the model.
- Resolve attribution settings from the process-level ChatGPT base URL, independent of per-thread or per-tool configuration overrides.
- Treat git attribution as contextual developer content when mapping model events.

## Testing

- Cover policy fetch retries, workspace switches, rollbacks, cold thread resumes with legacy instructions, MCP tool calls, and prompt-debug output.

GitOrigin-RevId: 57d182c432c20d7c1c6c429057b6163c9f32088d

codex-rs/core/tests/suite/prompt_debug_tests.rs

@@ -4,6 +4,7 @@ use anyhow::Result;
 use codex_core::build_prompt_input;
 use codex_core::config::ConfigBuilder;
 use codex_core::config::ConfigOverrides;
+use codex_extension_api::ExtensionRegistryBuilder;
 use codex_home::CodexHomeUserInstructionsProvider;
 use codex_protocol::models::ContentItem;
 use codex_protocol::models::ResponseItem;
@@ -32,7 +33,6 @@ async fn build_prompt_input_includes_context_and_user_message() -> Result<()> {
     let user_instructions_provider = Arc::new(CodexHomeUserInstructionsProvider::new(
         config.codex_home.clone(),
     ));
-
     let input = build_prompt_input(
         config,
         vec![UserInput::Text {
@@ -40,6 +40,7 @@ async fn build_prompt_input_includes_context_and_user_message() -> Result<()> {
             text_elements: Vec::new(),
         }],
         /*state_db*/ None,
+        Arc::new(ExtensionRegistryBuilder::new().build()),
         user_instructions_provider,
     )
     .await?;
@@ -74,6 +75,5 @@ async fn build_prompt_input_includes_context_and_user_message() -> Result<()> {
             text.contains(TEST_INSTRUCTIONS)
         })
     }));
-
     Ok(())
 }