## Summary
Now that bumpalo has been inlined into oxc_allocator (#18168), this PR cleans up comments and documentation that still reference bumpalo as an external dependency.
- Update module docs in `bump.rs` and `bumpalo_alloc.rs` to say "originally derived from" instead of "ported from"
- Remove obsolete comments about bumpalo version pinning in `from_raw_parts.rs`
- Update inline comments in `allocator.rs` from "delegates to bumpalo" to "it's a small function"
- Remove outdated TODO about replacing bumpalo in `tracking.rs`
- Update `ARCHITECTURE.md` and parser docs to reference `oxc_allocator` instead of bumpalo
- Clean up bumpalo references in other crates (`oxc_semantic`, `oxc_data_structures`, `apps/oxlint`, `napi/parser`, `tasks/ast_tools`)
## Test plan
- [x] `cargo check -p oxc_allocator` passes
- [x] `cargo test -p oxc_allocator` passes
- [x] Changes are documentation/comment only - no functional changes
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