phase-1: scaffold platform foundation structure and architecture governance

docs/architecture/foundation/adr/ADR-001-platform-model.md

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+# ADR-001: Platform Model and Tenancy Strategy
+
+Status: Accepted
+Date: 2026-07-03
+
+## Context
+
+The existing repository has evolved from marketplace website delivery.
+The target product is Marketplace-as-a-Service with unlimited tenants on one runtime.
+
+## Decision
+
+Adopt a platform runtime model:
+
+- One Angular application serves all tenants.
+- Tenant identity is resolved by backend from request Host.
+- Frontend does not pass tenant id or project key.
+- Frontend starts by requesting GET /bootstrap.
+- Tenant-specific website, builder, and backoffice behavior derives from bootstrap configuration.
+
+## Consequences
+
+Positive:
+
+- Tenant onboarding becomes configuration-driven.
+- Eliminates tenant forks and branch divergence.
+- Strong separation of platform engine and tenant data.
+
+Negative:
+
+- Requires strict discipline against tenant conditionals in UI code.
+- Requires robust bootstrap schema governance.
+
+## Compliance Requirements
+
+- No environment-based tenant branching in presentation logic.
+- No tenant-specific routes hardcoded in feature components.
+- Tenant behavior is represented in typed configuration contracts.