fix: keep projected lines within ruled tables

[Chengyunlai]

Summary

• pass detected ruled-table rectangles into projected-line construction
• prevent same-y text from different table rectangles from becoming one projected line
• keep each table’s projected lines contiguous so ruled-table consumption sees normal reading order
• add a focused regression test covering both line separation and left-table-before-right-table ordering

Root cause

PR run-llama#392 separates the vector geometry for side-by-side ruled grids, but the projection stage still groups text from both rectangles into the same line. Each ruled candidate then sees text from the adjacent table as overhang and fallback detection merges the tables again.

This follow-up uses the already-detected table rectangles as structural grouping boundaries. It does not globally change y tolerance, so ordinary multi-column text behavior is unchanged.

Reproduction

• Issue: Side-by-side ruled tables still share projected text lines run-llama/liteparse#414
• Public synthetic PDF: https://github.com/Chengyunlai/liteparse/blob/codex/repro-issue-414-side-by-side-tables/reproductions/issue-414/side-by-side-ruled-tables.pdf
• SHA-256: e9b56e7a3f1d990d9e1f1b63b46e5d89b8ce1afaa85c9e17a09d83d1f5563b8d

On that document, the base of run-llama#392 produces one merged 6-column table. This follow-up produces two independent 3-column Markdown tables.

Validation

• cargo fmt --all -- --check
• cargo test -p liteparse projected_lines_do_not_span_independent_side_by_side_tables --lib -- --nocapture (1 passed)
• cargo test -p liteparse --lib (295 passed)
• full workspace release build through the repository Dockerfile
• end-to-end parse of the public PDF with --format markdown --no-ocr

Dependency

This is intentionally a stacked draft based on codex/fix-separated-grid-components, the head branch of run-llama#392. It should be retargeted or rebased after run-llama#392 is resolved.

[Chengyunlai]

Superseded by the completed projection fix now included directly in run-llama#392 at 26b79a6. The published reproduction, A/B evidence, and expanded regression coverage are documented on the upstream PR and in run-llama#414.