CLI improvements: --json output, filters, arch-search, ecal-score, deck fixes

6 CLI improvements from MCP integration testing + deck bug fixes:

- kb_cli.py: --json on search, new arch-search and ecal-score subcommands,
  _load_yaml handles multi-document YAML (fixes health command on 32 files)
- findings_cli.py: --json on search/list/stats, filter flags on search
  (--product, --severity, --tag, --client, --status, --category)
- validate-architecture.py: --profile optional, --output defaults to stdout
- common-objections.yaml + ecal-artefacts-catalog.yaml: merge front matter
- oci_deck_gen.py: fix slide 9 cost_notes char iteration, fix slide 12
  migration field mapping (duration/milestones), dynamic phase spacing
- proposal-spec.yaml: replace real name with fictional Carlos Mendoza

All 14 skill options validated with generated deliverables.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

kb/patterns/ecal-artefacts-catalog.yaml

@@ -1,10 +1,8 @@
----
 last_verified: 2026-03-18
 pattern:
   id: ecal-artefacts-catalog
   name: "ECAL 3.1 Artefacts Catalog"
   category: governance
----
 
 description: >
   Complete catalog of ECAL 3.1 artefacts across all 9 steps.