agents-chat-starter: spawn PUT goes to the durable-streams proxy, so no entity is created and agents never wake

### What happens

Follow the starter's Quick Start, create a room, and send a message. No philosopher ever replies. Nothing reports an error. `POST /api/rooms` returns `{"agentCount": 1}` and the spawn PUT returns `201 Created`.

The spawn call in `examples/agents-chat-starter/src/server/index.ts` PUTs to the bare entity path:

```ts
const entityUrl = `/${type}/${agentId}`
const putRes = await fetch(`${AGENTS_URL}${entityUrl}`, { method: `PUT`, ... })
```

On the current agents-server, that path never reaches the entity API. `packages/agents-server/src/routing/global-router.ts` sends `/_electric/*` to the internal router and everything else to the durable-streams proxy:

```ts
globalRouter.all(`/_electric/*`, internalRouter.fetch)
globalRouter.all(`*`, durableStreamsRouter.fetch)
```

So the PUT creates a raw durable stream named `/socrates/` and returns `201`. No entity is created, no dispatch subscription is registered, and the agent never wakes. The only route that creates an entity is `PUT /_electric/entities/:type/:instanceId` (`packages/agents-server/src/routing/entities-router.ts`).

### Repro

Against `@electric-ax/agents-server` 0.6.3 (run via `pnpm dlx`, embedded streams, port 4510) with the starter's backend running so the `socrates`/`camus`/`simone` types are registered:

```console
$ curl -s -o /dev/null -w '%{http_code}\n' -X PUT localhost:4510/socrates/repro-bare \
-H 'content-type: application/json' \
-d '{"args":{"chatroomId":"repro"},"initialMessage":"You have joined."}'
201

$ curl -s localhost:4510/_electric/entities
# only the principal entity; /socrates/repro-bare is not there

$ curl -s -X PUT localhost:4510/_electric/entities/socrates/repro-entity \
-H 'content-type: application/json' \
-d '{"args":{"chatroomId":"repro"},"initialMessage":"You have joined."}'
{"url":"/socrates/repro-entity","type":"socrates","status":"idle","streams":{"main":"/socrates/repro-entity/main"},"dispatch_policy":{"targets":[{"url":"http://localhost:4710/webhook","type":"webhook",...
```

After the second PUT the entity appears in `/_electric/entities`, the dispatch webhook is registered, and the first wake runs the handler. Nothing at all happens after the first PUT.

### Why it broke

The starter was correct when it was written. At the original Electric Agents commit (#4151), the server matched bare `/{type}/{name}` paths and spawned on PUT. The routing refactor in #4307 moved entity creation under `/_electric/entities` and pointed the catch-all at the durable-streams proxy. The starter (added in #4199, before the refactor) kept the old path, so it has been silently broken since #4307. The failure mode is nasty because the proxy answers `201` and the starter's `putRes.ok` check passes.

Everything else in the repo already uses the canonical path: `ctx.spawn` through `runtime-server-client.ts` `spawnEntity()`, the `electric-ax` CLI (`entity-api.ts`), and the conformance DSL, which prefixes `/_electric/entities` onto every entity request.

### Fix

Point the starter's spawn fetch at `${AGENTS_URL}/_electric/entities/${type}/${id}`, and fix the same snippet in the starter's `AGENTS.md` ("Entity Bootstrap" section). PR incoming.

Versions: `@electric-ax/agents-server` 0.6.3, `@electric-ax/agents-runtime` 0.6.3, repo `main` at 9e3af10c3.

A separate, smaller problem found on the way: `pnpm install` on a freshly scaffolded copy (`npx electric-ax agents init`) fails because the template's `package.json` pins `"@electric-ax/agents-runtime": "workspace:*"`, which does not resolve outside the monorepo. Happy to file that separately.

Start with the spawn fetch in examples/agents-chat-starter/src/server/index.ts and the Entity Bootstrap snippet in the starter's AGENTS.md. Compare their request path with the entity route in packages/agents-server/src/routing/entities-router.ts, then run the Quick Start to confirm the entity appears in /_electric/entities and the agent wakes after a message.

Written by the indexing model from the issue text.