docs(architecture): persona template consolidation pattern + proposal

Document how admin/merchant/store templates share a single shared/ body
partial while keeping their three separate base templates. Covers:

- The wrapper/partial split and why the three base templates must stay
  separate (nav + permissions isolation).
- The scope contract: pass strings + booleans only, no macro objects,
  no `persona` enum.
- The backend mirror: services scope-agnostic, routes inject scope via
  auth deps, same Pydantic shape across personas.
- Legit exceptions and the heuristic for when to keep a template
  standalone (multi-tenant aggregators, persona-unique features).
- Forward reference to the TPL-016 architecture rule.

Adds both docs to mkdocs nav under Architecture and Proposals
sections.

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

mkdocs.yml

@@ -61,6 +61,7 @@ nav:
       - Media Architecture: architecture/media-architecture.md
       - Metrics Provider Pattern: architecture/metrics-provider-pattern.md
       - Multi-Platform CMS: architecture/multi-platform-cms.md
+      - Persona Template Consolidation: architecture/persona-template-consolidation.md
       - Tenancy Module Migration: architecture/tenancy-module-migration.md
       - Widget Provider Pattern: architecture/widget-provider-pattern.md
       - Architecture Violations Status: architecture/architecture-violations-status.md
@@ -339,6 +340,7 @@ nav:
       - Hosting Cascade Delete: proposals/hosting-cascade-delete.md
       - Hosting Site Creation Fix: proposals/hosting-site-creation-fix.md
       - Loyalty Go-Live Readiness: proposals/loyalty-go-live-readiness.md
+      - Persona Template Consolidation: proposals/persona-template-consolidation.md
       - Loyalty Phase 2 Interfaces: proposals/loyalty-phase2-interfaces-plan.md
       - Loyalty Program Analysis: proposals/loyalty-program-analysis.md
       - Merchant Intake Checklist: proposals/merchant-intake-checklist.md