Stop filtering model tools in js_repl_tools_only mode (#12069)

## Summary
This change removes tool-list filtering in `js_repl_tools_only` mode and
relies on the normal model tool descriptions, while still enforcing that
tool execution must go through `js_repl` + `codex.tool(...)`.

## Motivation
The previous `js_repl_tools_only` filtering hid most tools from the
model request, which diverged from standard tool-list behavior and made
signatures less discoverable. I tested that this filtering is not
needed, and the model can follow the prompt to only call tools via
`js_repl`.

## What Changed
- `filter_tools_for_model(...)` in `core/src/tools/spec.rs` is now a
pass-through (no filtering when `js_repl_tools_only` is enabled).
- Updated tests to assert that model tools are not filtered in
`js_repl_tools_only` mode.
- Updated dynamic-tool test to assert dynamic tools remain visible in
model tool specs.
- Removed obsolete test helper used only by the old filtering
assertions.

## Safety / Behavior
- This commit does **not** relax execution policy.
- Direct model tool calls remain blocked in `js_repl_tools_only` mode
(except internal `js_repl` tools), and callers are instructed to use
`js_repl` + `codex.tool(...)`.

## Testing
- `cargo test -p codex-core js_repl_tools_only`
- Manual rollout validation showed the model can follow the `js_repl`
routing instructions without needing filtered tool lists.



#### [git stack](https://github.com/magus/git-stack-cli)
- 👉 `1` https://github.com/openai/codex/pull/12069
- ⏳ `2` https://github.com/openai/codex/pull/10673
- ⏳ `3` https://github.com/openai/codex/pull/10670

codex-rs/core/src/codex.rs

@@ -4869,8 +4869,7 @@ async fn run_sampling_request(
 
     let model_supports_parallel = turn_context.model_info.supports_parallel_tool_calls;
 
-    let tools =
-        crate::tools::spec::filter_tools_for_model(router.specs(), &turn_context.tools_config);
+    let tools = router.specs();
     let base_instructions = sess.get_base_instructions().await;
 
     let prompt = Prompt {