Aliases for newer OCI services without toolkit icons (Redis, PostgreSQL)

Diego pointed at examples/output-ashburn-redis-oke and asked: does
Oracle ship a Redis icon for drawio? Answer: NO. Confirmed against
both libraries:
  - kb/diagram/oci-icons.json (OCI Toolkit v24.2)         → 0 hits
  - kb/diagram/oci-pptx-icons-index.json (OCI_Icons.pptx) → 0 hits
Same for OCI Cache, Valkey, OCI PostgreSQL — all are GA after the
toolkit shipped.

Oracle's own reference architecture
``modernize-app-dev-oci-postgresql-redis-opensearch`` works around
this by embedding inline SVG vector data into ``shape=stencil(...)``
cells — there is no reusable named stencil. The closest reusable
match is the generic ``database`` icon (8 cells in oci-icons.json,
the canonical "Database" stencil).

Persistent fixes:

- TYPE_TO_ICON (PPTX) and ICON_TYPE_ALIASES (drawio) both gain
  aliases for ``redis`` / ``oci_cache`` / ``oci_cache_with_redis`` /
  ``cache`` / ``valkey`` / ``postgresql`` / ``postgres`` /
  ``oci_postgresql`` → ``database``. Plus ``opensearch`` →
  ``database_opensearch`` (which exists) on the PPTX side.

- SKILL.md option 2 step 3 documents the convention: when an OCI
  service doesn't have a toolkit icon, use the generic stencil and
  pair with an explicit ``label:`` carrying the real service name
  (e.g. ``label: "OCI Cache (Redis)"``). When Oracle ships a v25+
  toolkit with these icons, update oci-icons.json + the alias tables
  and the next render picks up the real icon automatically.

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

tools/oci_diagram_gen.py

@@ -856,6 +856,19 @@ class OCIDiagramGenerator:
         "terraform": ["resource_manager"],
         "oac": ["analytics"],
         "oic": ["integration"],
+        # Newer OCI services not yet in OCI Toolkit v24.2 — fall back to
+        # the generic ``database`` stencil. Oracle's own ref archs do
+        # the same (custom inline SVG over the generic icon) until the
+        # toolkit ships dedicated stencils. The agent should pair these
+        # with an explicit ``label:`` (e.g. "OCI Cache (Redis)").
+        "redis": ["database"],
+        "oci_cache": ["database"],
+        "oci_cache_with_redis": ["database"],
+        "cache": ["database"],
+        "valkey": ["database"],
+        "postgresql": ["database"],
+        "postgres": ["database"],
+        "oci_postgresql": ["database"],
     }
 
     @classmethod