Add ISO/ZIP acquisition pipeline (ams.acquire worker)

Closes the chain from a game file to a catalog entry: unpack an ISO/ZIP,
content-identify the engine DLL (CMC_ObjectsContainer marker in RTTI, so a
renamed file is still found), hash it (sha256 + md5 + optional ssdeep via
ppdeep), run Ghidra headless with the extractor, enrich and import the snapshot.

- unpack.py: bsdtar (ISO9660 + ZIP) with a pure-Python zipfile fallback
- identify.py: content-based engine-DLL picker + hashing
- ghidra.py: analyzeHeadless launcher discovery + post-script run
- pipeline.py: orchestration with injectable extract_fn; sink db|http|none
- cli.py: python -m ams.acquire (incl. --identify-only dry run)
- tests: 7 new (forged PE markers + stubbed extractor) -> 18/18

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

ams/acquire/__init__.py

@@ -0,0 +1,7 @@
+"""Acquisition pipeline: game archive (ISO/ZIP) or loose DLL → engine snapshot → catalog."""
+
+from __future__ import annotations
+
+from .pipeline import AcquireError, AcquireResult, acquire
+
+__all__ = ["acquire", "AcquireResult", "AcquireError"]