Docs: dispatch loop roles as in-thread subagents

[joesobo]

Summary

• define role execution as in-thread Codex subagent dispatch from the Orchestrator
• keep the Orchestrator responsible for state, routing, human gates, and handoff decisions
• clarify that role subagents own role details and write the substantive role-boundary handoff entries
• keep the handoff file as shared state between Orchestrator and role subagents

Cleanup context

• discarded the second C# loop attempt because the Orchestrator did the Specifier work itself
• closed PR Trello 201: C# Upgrade #273 and removed the C# branch/worktree
• moved the C# Trello card back to Todo with a note

Checks

• rg scan for stale self-execution wording
• git diff --check

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