docs(how-to): split the walkthrough into docs/how-to/ + add the business-workflow chapter

Decompose the single docs/how-to.md into an indexed 5-chapter guide under
docs/how-to/: README (index/pitch/teaser/TOC), 01 the company, 02 it starts
with you, 03 the cells build it, 04 the last call and the loop. Image/video
paths rewritten to ../, inter-chapter nav added, the Prompter-build screenshots
preserved. Adds a new chapter 05 — the business workflow: the charter, the
Cockpit, the Secretary, and the web-research / strategy-engine config toggles,
with the end-to-end 'feel it' walkthrough. README links repointed to
docs/how-to/README.md. All image links verified; reflow-check clean.

README.md

@@ -66,7 +66,7 @@ One full loop, put simply:
 
 **— Full circle —**
 
-**[See the full walkthrough, with screenshots →](docs/how-to.md)**
+**[See the full walkthrough, with screenshots →](docs/how-to/README.md)**
 
 **[Or watch the full panel walkthrough (video) →](docs/videos/panel-full-walkthrough.mp4)**
 
@@ -93,7 +93,7 @@ roboco/
 ├── agents/
 │   └── prompts/                 # Agent system prompts (roles, teams, identities)
 ├── docs/
-│   ├── how-to.md               # Visual walkthrough of the workflow
+│   ├── how-to/                 # Visual walkthrough — 5-chapter guide (start at README.md)
 │   └── rag/                     # Agent knowledge base (indexed into RAG)
 ├── alembic/                     # Database migrations
 ├── CLAUDE.md                    # Claude Code guidance