worker: optional PyGhidra back-end for Ghidra 11.4+/12.x (no Jython)

The .py extractor runs fine under PyGhidra in the GUI; only `analyzeHeadless`
doesn't init PyGhidra. Add an env-gated CPython path so modern Ghidra works headless:

- ghidra.run_extractor_pyghidra(): runs the same GhidraScript via pyghidra.run_script
  (boots Ghidra in-process, imports+analyses, getScriptArgs()=[out_path]); run_extractor
  dispatches to it when AMS_USE_PYGHIDRA is set. No script changes needed.
- worker image installs pyghidra + sets GHIDRA_INSTALL_DIR; compose exposes
  AMS_USE_PYGHIDRA (default off). Jython path stays the default and untouched.
- README documents both variants (Jython <=11.3.x vs PyGhidra 11.4+/12.x).
- test: AMS_USE_PYGHIDRA routes to the PyGhidra back-end (clear error if pkg missing).

35/35 tests pass.

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

docker/worker.Dockerfile

@@ -29,6 +29,7 @@ RUN wget -q "$GHIDRA_URL" -O /tmp/ghidra.zip \
 RUN pip3 install --no-cache-dir --upgrade pip setuptools wheel
 
 ENV GHIDRA_HOME=/opt/ghidra
+ENV GHIDRA_INSTALL_DIR=/opt/ghidra
 ENV AMS_GHIDRA_SCRIPTS=/app/ghidra_scripts
 ENV AMS_UPLOAD_DIR=/data/uploads
 
@@ -38,7 +39,9 @@ COPY ams ./ams
 COPY ghidra_scripts ./ghidra_scripts
 COPY snapshots ./snapshots
 
-RUN pip3 install --no-cache-dir ".[api,acquire,worker]"
+# pyghidra enables the CPython back-end (set AMS_USE_PYGHIDRA=1) for Ghidra 11.4+/12.x, which
+# dropped Jython. Harmless when unused; the default Jython path doesn't import it.
+RUN pip3 install --no-cache-dir ".[api,acquire,worker]" pyghidra
 
 # Drain the 'acquire' queue. Shell form so $REDIS_URL expands at runtime.
 CMD rq worker --url "${REDIS_URL:-redis://redis:6379/0}" acquire