feat(api): add backend with kanban, docs store, and orchestrator

Introduce the @void-nav/api Hono + SQLite backend that powers the docs site:
a persisted implementation board (kanban), a custom documentation-pages store
with AI beautify, and an agentic orchestrator that runs `pi` agents per card.

The orchestrator spawns `pi --mode rpc` inside an isolated git worktree per run,
streams slim events over SSE, and lets the agent drive the board/docs via
token-gated internal endpoints (all SQLite writes stay in-process). Interrupted
runs are reconciled to "stopped" on boot.

Workspace wiring: root `dev:api`/`dev:web` scripts with `concurrently`, the
docs Vite `/api` proxy, and `.worktrees/` gitignore.

apps/docs/vite.config.ts

@@ -1,8 +1,16 @@
-import { defineConfig } from "vite";
 import tailwindcss from "@tailwindcss/vite";
+import { defineConfig } from "vite";
 
 export default defineConfig({
   plugins: [tailwindcss()],
+  // Proxy API requests to the @void-nav/api dev server (apps/api) so the docs
+  // site and its backend share one origin in dev — no CORS, one command to run
+  // both via `pnpm dev:web`.
+  server: {
+    proxy: {
+      "/api": "http://localhost:3001",
+    },
+  },
   esbuild: {
     jsx: "automatic",
     jsxImportSource: "react",