fix: add file size limit to FileModel to prevent multi-GB allocations

[warp-dev-github-integration]

Summary

Adds a 256 MB file size limit to FileModel to prevent multi-gigabyte memory allocations when opening or reloading very large files.

Problem

Sentry issue 7259255054 shows 24.18 GB of in-use memory with 99.27% from async_fs::read_to_string via the blocking::Executor thread pool. The heap profile shows the allocation path:

blocking::Executor::main_loop
  → async_fs::read_to_string<&PathBuf>
    → std::fs::read_to_string::inner
      → alloc::raw_vec::RawVecInner::finish_grow  (24 GB)

FileModel::open(), read_content_for_file(), and reload_file_paths() all use async_fs::read_to_string without any size check. When a user opens or the file-watcher detects changes to a very large file (logs, binaries, database dumps, etc.), the entire content is read into memory as a String.

Changes

• warp_util/src/file.rs: Added FileTooLarge { size, limit } variant to FileLoadError
• warp_files/src/lib.rs:
  • Added MAX_READABLE_FILE_SIZE constant (256 MB)
  • Added check_file_size() async helper
  • Guarded FileModel::open() with size check before read_to_string
  • Guarded FileModel::read_content_for_file() with size check
  • Guarded FileModel::reload_file_paths() with size check (logs warning and skips)
• app/src/ai/blocklist/action_model/execute.rs: Added FileTooLarge arm to exhaustive match in read_binary_file_context

Validation

• cargo check --workspace passes
• cargo clippy -p warp_files -p warp_util -- -D warnings passes

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CHANGELOG-BUG-FIX: Fixed excessive memory usage when opening very large files by adding a 256 MB file size limit

Conversation: https://staging.warp.dev/conversation/99f355e9-9bd4-4dbf-ae68-c81bc1db01ae
Run: https://oz.staging.warp.dev/runs/019e8793-6d32-723a-bbc1-75d4c4694915
This PR was generated with Oz.