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/summary.md

@@ -1,9 +1,9 @@
-# Beslutningsnotat — ANPR-trafikkanalyse
+# Beslutningsnotat — Demosystem
 
-System: ANPR-trafikkanalyse (Statens vegvesen)
+System: Demosystem (Acme AS)
 Dato: 2026-04-30
 Til: Direktør for Digital og IT
-Fra: KI-seksjonen
+Fra: AI-teamet
 
 ## Verdict
 
@@ -34,7 +34,7 @@ Arkitekturen er teknisk solid og økonomisk forsvarlig (P50 NOK 1.7M/år), men c
 
 ## Restrisiko
 
-Etter foreslåtte tiltak: medium. Hovedeksponering: bias mot utenlandske kjennemerker krever løpende monitoring.
+Etter foreslåtte tiltak: medium. Hovedeksponering: bias mot utenlandske objekt-ID krever løpende monitoring.
 
 ## Anbefaling