Bootstrap design specs

[edwin-zvs]

Summary

• create the initial specs/ design decision records
• capture durable decisions from recent session, widget, web UI, TUI, harness, provider retry, memory, and tool-layer work
• keep the specs normative and intent-focused, without current-code anchors or implementation notes

Specs Added

• sessions as the core unit
• orchestrator as a session
• session widgets as UI state
• widget renderers owning interaction semantics
• terminal reconnect preserving live state
• resize/restart avoiding full-history refeed
• visible user session list actions
• built-in harness command overrides
• transient provider error retries
• durable shared memory
• shared tooling across harnesses

Tests

• git diff --check
• searched specs/ for current-code anchors such as paths, function names, and env vars