Remove stale files and prune CLAUDE.md of nonexistent code references (apache#115)

- Delete claude-progress.txt, QUICK-START.md, task_list.json, orc-predicate-pushdown.allium
- Remove CLAUDE.md references to OrcFileFragment, OrcSchemaManifest,
  BuildOrcSchemaManifest, GetOrcColumnIndex, StripeIterationLogic (none exist)
- Remove "Python-Level Gaps" section referencing nonexistent predicate pushdown types
- Fix test file line counts to match actual source

Author: cbb330

CLAUDE.md

@@ -96,8 +96,8 @@ ctest --label-regex unittest --output-on-failure --parallel <nproc> --repeat unt
 
 | Binary | Source File | What It Tests |
 |--------|------------|---------------|
-| `arrow-orc-adapter-test` | `cpp/src/arrow/adapters/orc/adapter_test.cc` (~1,259 lines) | Low-level adapter: type conversion, read/write roundtrip, column statistics extraction |
-| `arrow-dataset-file-orc-test` | `cpp/src/arrow/dataset/file_orc_test.cc` (~331 lines) | Dataset layer: format inspection, scanning, schema manifest building, column index resolution |
+| `arrow-orc-adapter-test` | `cpp/src/arrow/adapters/orc/adapter_test.cc` (~1,182 lines) | Low-level adapter: type conversion, read/write roundtrip, column statistics extraction |
+| `arrow-dataset-file-orc-test` | `cpp/src/arrow/dataset/file_orc_test.cc` (~96 lines) | Dataset layer: format inspection, scanning |
 
 ### C++ Test Patterns
 
@@ -107,19 +107,6 @@ Tests use Google Test with Arrow's fixture mixin framework:
 - **`TestOrcFileFormat`** (inherits `FileFormatFixtureMixin<OrcFormatHelper>`) — basic format tests: `Inspect`, `IsSupported`, `CountRows`, `FragmentEquals`
 - **`TestOrcFileFormatScan`** (inherits `FileFormatScanMixin<OrcFormatHelper>`, parameterized) — scan tests: `ScanRecordBatchReader`, `ScanBatchSize`, `ScanProjected`, `ScanProjectedNested`, `ScanWithPushdownNulls`, etc.
 
-Custom tests for the predicate pushdown work:
-- `BuildSchemaManifest_FlatSchema` / `BuildSchemaManifest_NestedSchema` — verifies Arrow-to-ORC column index mapping
-- `GetOrcColumnIndex_TopLevelFields` / `GetOrcColumnIndex_NestedFields` — verifies `FieldRef` resolution through the manifest
-- `StripeIterationLogic` — placeholder confirming empty stripe list = read-all path
-
-These custom tests forward-declare internal functions for white-box testing:
-```cpp
-namespace internal {
-Result<std::shared_ptr<OrcSchemaManifest>> BuildOrcSchemaManifest(...);
-std::optional<int64_t> GetOrcColumnIndex(...);
-}
-```
-
 ### CMake Wiring
 
 In `cpp/src/arrow/dataset/CMakeLists.txt`:
@@ -225,10 +212,6 @@ Located in `python/pyarrow/tests/data/orc/`:
 - Corresponding `*.jsn.gz` files with expected values
 - Sourced from Apache ORC examples: https://github.com/apache/orc/tree/main/examples
 
-### Python-Level Gaps
-
-The new C++ predicate pushdown types (`OrcFileFragment`, `OrcSchemaManifest`, statistics APIs, etc.) have **no Python bindings yet**. The existing Cython files only wrap the original upstream `ORCFileReader`/`ORCFileWriter`. Exposing predicate pushdown to Python would require new declarations in `_orc.pxd` and wrappers in `_dataset_orc.pyx`.
-
 ---
 
 ## CI Configuration