feat: lib-agent-dock-ui — global assistant dock

@crema/agent-dock-ui — a floating Sparkles FAB that opens a right-side
slide-over chat with an agents-platform agent. Extracted from
skyai-finance (the canonical dock) and made app-agnostic.

The shell, threading, compose box, and rich-block rendering (via
@crema/agent-ui's MessageBody) live here; the app injects identity
(resolveAgents), context (getPageContext → structured PageContext),
and transport (auth closed over inside it — the dock never sees a
token). Self-contained: raw slide-over + buttons styled with theme
tokens, no app-local shadcn dependency. Page context travels as a
structured field, never concatenated into the message.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

README.md

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+# lib-agent-dock-ui
+
+`@crema/agent-dock-ui` — the global **assistant dock**: a floating
+Sparkles FAB that opens a right-side slide-over chat with an
+agents-platform agent.
+
+The dock runs **in-process** in the host app (it needs DOM access for
+rich-block rendering and the action bus), so it ships as a lib, not an
+iframe or a CDN widget. The shell, threading, compose box, and rich-block
+rendering live here; the app injects:
+
+- **identity** — `resolveAgents()` returns the agent(s) the user can talk
+  to. One → no picker; many → a dropdown.
+- **context** — `getPageContext()` returns a structured `PageContext`
+  (`{route, resource?, label?}`). It travels to the platform as its own
+  field, never concatenated into the message, so page content can't
+  masquerade as a user instruction.
+- **transport** — `AgentDockTransport.chat()`. Auth is closed over inside
+  the transport (the app builds it from its `@crema/arcadia-agents-client`
+  instance); the dock never sees a token.
+
+## Usage
+
+```tsx
+import { AgentDock } from "@crema/agent-dock-ui"
+import { chat, listAgents } from "~/lib/api/arcadia"
+
+<AgentDock
+  transport={{ chat }}
+  resolveAgents={() => listAgents(tenantId, { archived: "false" })}
+  defaultAgentId={profile.defaultAgentId}
+  getPageContext={() => ({ route: location.pathname })}
+  onExpand={({ agentId }) => navigate(`/agents/${agentId}/chat`)}
+  hidden={isChatRoute}
+/>
+```
+
+Mount once, near the app root. `hidden` is app-computed per-route
+suppression. `onExpand` is optional — omit it to hide the ⤢ button.
+
+## Dependencies
+
+- `@crema/agent-ui` — `MessageBody` (rich-block rendering)
+- `react`, `lucide-react`
+
+Theme contract: consumes the `--chat-user-bg/-fg` and
+`--chat-assistant-bg/-fg/-border` tokens (every Crema theme defines them).