chore(ms-ai-architect): scrub identifying references from fixtures + remove screenshots

Removes:
- All 6 PNG screenshots (playground/screenshots/) and the capture script
  (scripts/screenshots/capture-playground.py).
- "Screenshots" section from plugin README.
- "Screenshot-suite" section from plugin CLAUDE.md.
- Screenshots bullet from marketplace root README's ms-ai-architect listing.

Scrubs the 17 synthetic fixtures + CHANGELOG/CLAUDE/README of identifying
references: organization names, government-agency names, agency-specific
terminology, sector-specific use cases. Replaced with generic placeholder
data ("Acme AS" / "Demosystem") that exercises the same parser archetypes.

Plugin's domain-target wording (Datatilsynet, offentlig sektor, offentlig
myndighet, rettshåndhevelse, NS 5814, Utredningsinstruksen, EU AI Act
Annex III categories) is intact — those describe the plugin's intended
audience, not any specific entity.

This is a cleanup commit. Earlier git history still contains the prior
references; force-push or rebase is required if scrubbing the history is
desired. That decision is out of scope here — please run it separately
if needed.

Verified post-scrub:
- bash tests/validate-plugin.sh -> 215/215 PASS
- bash tests/run-e2e.sh --playground -> 240/240 PASS (170 + 70)

plugins/ms-ai-architect/playground/test-fixtures/cost.md

@@ -1,6 +1,6 @@
-# Kostnadsestimat — ANPR-trafikkanalyse
+# Kostnadsestimat — Demosystem
 
-System: ANPR-trafikkanalyse (Statens vegvesen)
+System: Demosystem (Acme AS)
 Periode: 12 måneder fra produksjonssetting
 Valuta: NOK
 
@@ -18,7 +18,7 @@ Valuta: NOK
 |-----------|-------------------|
 | Azure AI Services (OCR + classification) | 64 000 |
 | Azure OpenAI (forklaringsmodell) | 28 000 |
-| Azure AI Search (indeks for kjøretøyregister) | 12 000 |
+| Azure AI Search (indeks for objektregister) | 12 000 |
 | Storage (blob + cosmos for audit) | 8 500 |
 | Compute (Container Apps for orchestration) | 11 000 |
 | Networking (Private Endpoints + egress) | 5 200 |
@@ -35,7 +35,7 @@ Valuta: NOK
 
 ## Kostnadsdrivere
 
-- Trafikkvolum: ~12 millioner ANPR-deteksjoner/mnd
+- Datavolum: ~12 millioner Demosystem-deteksjoner/mnd
 - Forklaring-prompt-tokens: ~250 tokens per flagged hendelse
 - Reservert kapasitet for 99.9% SLA