Load tiny-agents from Hub (#1472)

As discussed offline, this PR moves the curated collection of
tiny-agents to the Hub. Agents must now be contributed to
https://huggingface.co/datasets/huggingface/tiny-agents. This will be
helpful to maintain the collection independently from the
`@huggingface/tiny-agents` releases. It also makes them available for
the incoming Python equivalent
(huggingface/huggingface_hub#3098).

File resolution is still the same:
1. if agent_id is a file => load it as a `agent.json` file
2. if agent_id is a directory => load from it
3. if agent_id is a subdirectory in
https://huggingface.co/datasets/huggingface/tiny-agents/tree/main =>
load from it
4. otherwise raise exception

Usage is still:

```bash
npx @huggingface/tiny-agents run "julien-c/flux-schnell-generator"
```

Author: Wauplin

packages/tiny-agents/README.md

@@ -85,10 +85,19 @@ npx @huggingface/tiny-agents run ./my-agent
 
 Voilà! 🔥
 
+
+## Tiny Agents collection
+
+Browse our curated collection of Tiny Agents at https://huggingface.co/datasets/tiny-agents/tiny-agents. Each agent is stored in its own subdirectory, following the structure outlined above. Running an agent from the Hub is as simple as using its `agent_id`. For example, to run the [`julien-c/flux-schnell-generator`](https://huggingface.co/datasets/tiny-agents/tiny-agents/tree/main/julien-c/flux-schnell-generator) agent:
+
+```bash
+npx @huggingface/tiny-agents run "julien-c/flux-schnell-generator"
+```
+
 > [!NOTE]
-> Note: you can open a PR in the huggingface.js repo to share your agent with the community, just upload it inside the `src/agents/` directory.
+> Want to share your own agent with the community? Submit a PR to the [Tiny Agents](https://huggingface.co/datasets/tiny-agents/tiny-agents/discussions) repository on the Hub. Your submission must include an `agent.json` file, and you can optionally add a `PROMPT.md` file. To help others understand your agent's capabilities, consider including an `EXAMPLES.md` file with sample prompts and use cases.
 
-### Advanced: Programmatic Usage
+## Advanced: Programmatic Usage
 
 ```typescript
 import { Agent } from '@huggingface/tiny-agents';

packages/tiny-agents/package.json

@@ -54,6 +54,7 @@
 		"@huggingface/inference": "workspace:^",
 		"@huggingface/mcp-client": "workspace:^",
 		"@huggingface/tasks": "workspace:^",
+		"@huggingface/hub": "workspace:^",
 		"@modelcontextprotocol/sdk": "^1.11.4",
 		"zod": "^3.25.7"
 	}