Nests: team rooms with core crows and borrowing

- Server: nests API, persistence, core-first picking, borrowed flag
  (built by the backend agent against EVENTS.md; tests pass with -race)
- UI: nests in the sidebar, one feed per nest, header shows the core
  team, New nest dialog, borrowed crows labeled, per-nest waiting count
- start.command: one-click local server in controlled mode (mock crows,
  localhost only, state in .crows/)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UQnSw4RRWp8uqpj3nsnnXF

README.md

@@ -38,6 +38,21 @@ curl localhost:8080/api/trust
 - UI development: run `crows serve`, then `cd ui && npm run dev` (Vite proxies `/api`). The crow art is `art/crow.svg`; the UI's `CrowView` mirrors `RIVE_CONTRACT.md`, so a Rive-backed view replaces the SVG stand-in later.
 - POST bodies are capped at 64 KB. Static files are served from `./web` when that folder exists.
 
+## Nests
+
+A nest is a room where a team of crows works together. Create one with its core crows; jobs in that nest use the core first and borrow from the rest of the flock when they need more (a murder of 3 in a 2-crow nest borrows one). The Sentry and Elder serve every nest.
+
+```
+curl localhost:8080/api/nests                     # {"roster": [...], "nests": [...]}
+curl -XPOST localhost:8080/api/nests -d '{"name":"Launch copy","crows":["Pepper","Inky"]}'   # 201, nest_id "launch-copy"
+curl -XPOST localhost:8080/api/lists -d '{"text":"- [ ] Should we launch on a Tuesday","nest_id":"launch-copy"}'
+./crows run todo.txt -nest launch-copy
+```
+
+- The default nest is `todo`, with an empty core: crows come from the whole flock and are never "borrowed".
+- `crow.flying` carries `borrowed: true` for a crow from outside the nest's core.
+- Names are 1–40 characters; `nest_id` is the name as a slug and must be unique (409 on a clash). 1–8 roster crows, no repeats, at most 20 nests. Nests are saved in `.crows/nests.json`.
+
 ## How an item flies
 
 1. **Sentry** classifies it: `solo` (one crow), `split` (2–4 subtasks in parallel), or `murder` (3 crows answer independently).