Add: download_decisive_appraisal_pdf MCP tool

The PDF host (free-justice.openapi.gov.il) requires the same x-client-id
header as the search API, so a normal browser click on the URL fails.
This tool carries the auth header automatically and saves the PDF to a
configurable local directory.

Safety properties:
- SSRF guard: only download from free-justice.openapi.gov.il and
  pub-justice.openapi.gov.il.
- Path-traversal guard: filename is reduced to its basename; arbitrary
  paths are stripped.
- Content-type guard: rejects 200-OK responses whose body is not a real
  PDF (gateway sometimes returns JSON-error 200s).
- Atomic write via .tmp + rename so partial downloads never replace the
  cached copy.
- Caches by destination path; re-downloads are no-ops unless overwrite=True.

DECISIVE_APPRAISER_DOWNLOAD_DIR env var configures the output dir
(default: ./downloads/decisive_appraisals). 6 new unit tests cover the
happy path, caching, and all four guards. End-to-end live test confirmed
a 1.4MB real PDF lands on disk with valid `%PDF-1.7` header.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

nadlan_mcp/config.py

@@ -176,6 +176,18 @@ class GovmapConfig:
             os.getenv("TOOL_SEARCH_DECISIVE_APPRAISALS_ENABLED", "true").lower() == "true"
         )
     )
+    tool_download_decisive_appraisal_pdf_enabled: bool = field(
+        default_factory=lambda: (
+            os.getenv("TOOL_DOWNLOAD_DECISIVE_APPRAISAL_PDF_ENABLED", "true").lower() == "true"
+        )
+    )
+
+    # Decisive Appraiser download settings
+    decisive_appraiser_download_dir: str = field(
+        default_factory=lambda: os.getenv(
+            "DECISIVE_APPRAISER_DOWNLOAD_DIR", "./downloads/decisive_appraisals"
+        )
+    )
 
     def __post_init__(self):
         """Validate configuration after initialization."""