docs: publish architecture and context graph overview

[codeyogi911]

What changed

• publish an accessible overview diagram of the implemented Morrow Desk V1 architecture
• add a detailed architecture-overview document and link it from the README and architecture reference
• document a proposed bounded context graph using a rebuildable D1 projection and optional Vectorize seed discovery
• update the roadmap while keeping external graph infrastructure evidence-gated

Why

Morrow needs a public, inspectable explanation of how operator agents, customer channels, deep business modules, and Cloudflare services fit together. Agents also need richer cross-module context without receiving raw tables, an unbounded graph dump, or mutation authority derived from relationships.

The proposal keeps business modules authoritative. D1 stores a disposable typed-edge projection, Vectorize returns candidate node IDs only, and a bounded context lens re-enters D1 and module authorization before returning cited, revisioned context.

Validation

• npm run check — 202 Worker tests and 2 production-configuration tests passed
• npm run scan:public
• xmllint --noout docs/assets/architecture-overview.svg docs/assets/context-graph.svg
• git diff --check
• rendered and visually inspected both SVGs
• independent architecture-truth and Cloudflare-platform reviews: PASS after revisions