[upstream-sync] ops_text module refactor: move output_positions and split elements (upstream PRs #1751, #1752)

[github-actions]

Upstream Change Summary

Type: architectural-change (refactor)
Difficulty: Easy
Recommendation: Adopt

Two related upstream refactors reorganized rust/ops_text/:

1. PR #1751: Moved output_positions.rs from split/ to the crate root of ops_text
2. PR #1752: Moved more elements out of the split module (by_separators, recursive splitters) to reduce module nesting

These are purely structural changes with no behavioral impact, but recoco-splitters should mirror the upstream module layout for easier future sync.

Upstream References

• PR #1751: refactor: move output_positions.rs to crate root cocoindex-io/cocoindex#1751 (move output_positions.rs to crate root)
• PR #1752: refactor: move more elements out of split module cocoindex-io/cocoindex#1752 (move more elements out of split module)
• Release: v0.3.35
• Upstream repo: https://github.com/cocoindex-io/cocoindex

Relevant Upstream Files / Areas

• rust/ops_text/src/output_positions.rs — moved to crate root
• rust/ops_text/src/split/mod.rs — elements moved out
• rust/ops_text/src/split/by_separators.rs
• rust/ops_text/src/split/recursive.rs
• rust/ops_text/src/lib.rs — updated re-exports

Recoco Considerations

• Maps to crates/recoco-splitters
• This is distinct from issue [upstream-sync] Move pattern-matcher module from core to splitters #96 (PatternMatcher move) — these are different structural changes within ops_text/recoco-splitters
• Low risk, purely structural — update mod.rs and lib.rs re-exports accordingly
• Verify public API surface of recoco-splitters is unchanged after re-export updates
• No feature-gating changes required

Integration Notes

Both PRs were merged on the same day (2026-03-11) and are clearly a coordinated cleanup. Apply them together. Check if any downstream code in recoco imports from the old module paths and update accordingly.