feat: support DataFusion paimon_incremental_query - #511

Purpose

Linked issue: close #506

This PR adds the DataFusion SQL surface for the batch incremental read APIs now available on main.

SELECT * FROM paimon_incremental_query('t', 0, 2);
SELECT * FROM paimon_incremental_query('t', 0, 2, 'diff');
SELECT rowkind, id, value FROM paimon_incremental_query('t$audit_log', 0, 2, 'changelog');

Brief change log

• Register TVF paimon_incremental_query in SQLContext
• 3-arg form defaults to auto; optional 4th arg: auto / delta / changelog / diff
• Delegate physical planning to core IncrementalScan / AuditLogTable
• Support $audit_log suffix for rowkind output
• Support projection and residual filters
• Resolve qualified table names against the named catalog; unqualified names follow the current catalog
• Update docs/src/sql.md with usage and examples

Tests

cargo test -p paimon-datafusion --test incremental_query
cargo fmt --all -- --check
cargo clippy -p paimon-datafusion --all-targets -- -D warnings

API and Format

• New SQL table function only; storage format unchanged
• Relies on the core incremental APIs already merged into main

Documentation

docs/src/sql.md documents registration, arguments, modes, and examples.