Diagram generation: ref-arch-driven procedure + spec validator + KB enrichment

The diagram path now follows a documented standard procedure (lookup
the closest Oracle Architecture Center reference → confirm components
→ author absolute_layout → spec validator → render → visually verify)
and ships persistent guardrails so layout regressions can't recur.

Persistent procedure changes (apply to all users, all sessions):
- tools/diagram_spec_validator.py — geometry checks (CONTAINER_TOO_THIN,
  CONTAINER_PADDING_VIOLATION, LABEL_OVERFLOW_PARENT) run BEFORE either
  renderer (drawio + PPTX). Catches the subnet-collapse / label-overflow
  bugs that the post-render drawio validator missed.
- tools/oci_diagram_gen.py + tools/oci_pptx_diagram_gen.py — call the
  spec validator before emitting any output. Adds mysql / mysql_heatwave
  type aliases.
- tools/archcenter_pattern_lookup.py — scores against cached page
  descriptions (not just the 1-line summary), supports --queries for
  multi-fragment composition, and applies synonym expansion via
  kb/architecture-center/synonyms.yaml so "LB HA cross AD" matches
  "load balancer high availability availability domain".
- kb/architecture-center/synonyms.yaml — canonical synonym table
  (load balancer, autonomous database, data guard, …) used by the
  lookup scorer.

KB enrichment:
- tools/archcenter_description_fetcher.py + 121 cached _description.md
  under kb/diagram/assets/archcenter-refs/<slug>/. Removes the runtime
  dependency on docs.oracle.com when authoring specs and feeds the
  pattern-lookup scorer.
- 110+ cached .drawio / .svg / .png references for offline reuse,
  plus the OCI Toolkit v24.2 import (kb/diagram/assets/oci-toolkit-drawio).

Documentation:
- docs/skill/output-formats.md — new "Standard diagram-generation
  procedure (MANDATORY)" + geometry rules + the new validator entry.
- SKILL.md option 2 — references the mandatory procedure.
- README.md — describes the spec validator, archcenter_pattern_lookup
  and description fetcher, and updates the KB-health table.

Tooling that backs the procedure (cumulative across recent sessions):
tools/archcenter_case_runner.py, archcenter_batch_driver.py,
archcenter_zip_downloader.py, drawio_visual_validator.py,
drawio_fidelity_eval.py, harvest_drawio_icon.py, import_oci_library.py,
oci_pptx_diagram_gen.py, oci_pptx_render.py, refresh_pptx_icon_index.py.

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

.gitignore

@@ -4,8 +4,8 @@ __pycache__/
 *.pyo
 output/
 *.pptx
-!examples/sample-output/*.pptx
 !templates/Oracle_PPT-template_FY26.pptx
+!kb/diagram/assets/OCI_Icons.pptx
 
 # OCI Toolkit binary (download from Oracle, don't commit)
 kb/diagram/OCI Library.xml
@@ -13,24 +13,10 @@ kb/diagram/OCI Library.xml
 # Build prompt (internal)
 COMPLETE-BUILD-PROMPT.md
 
-# Client-specific examples (never commit customer data)
-examples/farma-sa-*
+# Ignore all examples content
+examples/
 
-# Skill-generated output folders (customer-specific, never commit)
-examples/output-*/
-
-# Exported screenshots (temporary)
-examples/*.png
-
-# Exported ppts
-examples/*.ppts
-
-# Exported diagrams
-examples/*.drawio
-
-# Exported YAML files
-examples/*.yaml
-
-# Exported PDFfiles
-examples/*.pdf
-examples/*.xlsx
+# Workspace / sandbox artifacts (never committed)
+tmp/
+.claude/scheduled_tasks.lock
+.claude/worktrees/