Adds chat_completions and transcription as SDK function columns, backed
by the existing rust_bridge test files. Adds a fourth strategy folder,
existing_e2e_test_sdk, that points at already-existing live-API SDK
tests (tests/ocr_tests/ as a whole folder, plus chat completion and
Whisper transcription tests) instead of writing new parity tests.
Extends selector_matches_node with trailing-slash folder selectors so
a whole test folder can back one matrix cell.
* test: add OCR python-to-rust test parity ledger
* feat: add ledger loader for OCR test parity data
* feat: add drift audit for OCR test parity ledger (WIP, untested)
* fix: correct drift in OCR test-parity ledger
Two entries referenced a typo'd Python test name, four duplicated entries already tracked under TestProxySecurityGuard, five real Python tests in test_rust_bridge.py were untracked, and three real Rust custom_logger tests were missing from rust_only_tests. Found by running validate_ledger.py's audit against the live repo.
* test: add regression coverage for the OCR ledger and audit script
Covers schema validation, AST/regex test enumeration, drift detection on both the Python and Rust sides, LedgerDriftError content, and a live-repo clean-audit guard against future drift.
* test: simplify ledger test to one drift-guard assertion
Replace the ledger-internals unit tests with a single test that runs the real audit against the live repo and asserts every OCR test is accounted for (mapped, unmapped-with-reason, or rust_only), printing the exact diff on failure.
* chore: move OCR test-parity ledger to core/ocr
validate_sub_methods/ mixes strategy-catalog metadata with the ledger. Ledger data belongs under a per-function core/<function>/ path instead.
* fix: point LEDGER_PATH at the new core/ocr location
