fix: compare DuckLake metadata paths on the same absolute file

[weicao]

Summary

Same-volume recreate of v0.3.0-dev.20260907.2 (055524a1) still failed ATTACH with stage=attach reason=driver_error.

The image entrypoint cds into DATA_PATH and leaves --datadir at .. The metadata skip compared ./ducklake.db with the absolute MYDUCK_DUCKLAKE_METADATA_PATH, so attachCatalogs still opened the catalog as a regular database.

Identify the catalog file with os.SameFile after Stat, with Abs/EvalSymlinks fallback. Ordinary catalogs in the data directory still ATTACH.

Empty named volume first start on 055524a1 passed without pre-chown. be2cd5bd and 055524a1 must not be promoted. Does not change v0.2.1 / latest. Does not touch PR #489.

Test

• go test ./catalog -count=1 -run 'TestAttachCatalogSkipsDuckLakeMetadata'

[leon-ape]

Independent review of exact head 0bc8b81.

Identity: GitHub verification=valid, unique parent cc1d245, tree f95784cc1345ff4654e1492c1b28d53876d7ca3e, 2 files (catalog/provider.go, catalog/provider_ducklake_test.go).

cc1d245 compared Clean(Join(dataDir, name)) to Clean(meta). The image entrypoint cds into DATA_PATH and leaves --datadir at ".", so ./ducklake.db does not match absolute MYDUCK_DUCKLAKE_METADATA_PATH and attachCatalogs still ATTACHed ducklake.db. That matches the 055524a1 same-volume recreate FIRST_RED.

This head identifies the catalog file with os.SameFile after Stat, with Abs/EvalSymlinks fallback. TestAttachCatalogSkipsDuckLakeMetadataRelativeDataDir covers datadir=. versus an absolute metadata path, skips ducklake, and still ATTACHes myduck.db.

Does not promote be2cd5bd / 055524a1. Does not change v0.2.1 / latest. Merge and CI classification remain with the author/PM. Image remount stays unproven until a new digest.