Add Swarm TUI v2 docs: gap assessment, design mock, PRD, and tech spec

[Last-emo-boy]

Motivation

• Capture the current implementation gap between the Swarm/Symphony runtime and the full distributed vision and provide a focused plan to evolve the TUI from a chat-centric surface to a collaboration cockpit.
• Define product and technical requirements for Topology Strip, Decision Trail, and collaboration shortcuts to increase observability and operability of multi-agent workflows.
• Provide a phased, low-risk rollout and rollback strategy so UI changes can be feature-flagged and validated without rewriting the renderer.

Description

• Add a gap assessment doc docs/SWARM_SYMPHONY_TUI_GAP_ASSESSMENT_2026-05-28.md that summarizes current runtime capabilities, risks, and product recommendations.
• Add a visual/interaction mock docs/TUI_DESIGN_MOCK_V2.md that defines screen wireframes, overlays, Decision Trail layouts, role tokens, and keyboard rhythms for o/n/b/r shortcuts.
• Add a product requirements doc docs/TUI_PRD_V2.md that specifies Topology Strip, collaboration shortcuts, Decision Trail semantics, success metrics, and phased release planning.
• Add a technical spec docs/TUI_TECH_SPEC_V2.md that names new files to implement (e.g. src/tui/components/TopologyStrip.tsx and TopologyStrip.test.tsx), defines TopologyStripModel and DecisionTrail types, overlay routes (overlay:ownership, overlay:negotiation, overlay:blackboard), telemetry events, and CI gate commands and rollback via SWARM_TUI_EXPERIMENTAL_COLLAB=0.

Testing

• No automated tests were executed as part of this documentation-only change.
• The tech spec enumerates CI tests that should be run before release, for example node --import tsx --test "src/tui/**/*.test.ts", node --import tsx --test src/evals/local-evals.test.ts, npm run release:gate, and npm run smoke.

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Codex Task