Add seeded task workspace creation

Current persistent tasks started with an empty workspace, which blocked the first useful host-to-task workflow in the task roadmap. This change lets task creation start from a host directory or tar archive without changing the one-shot VM surfaces.

Expose source_path on task create across the CLI, SDK, and MCP, add safe archive upload and extraction support for guest and host-compat backends, persist workspace_seed metadata, and patch the per-task rootfs with the bundled guest agent before boot so seeded guest tasks work without republishing environments. Also switch post--- command reconstruction to shlex.join() so documented sh -lc task examples preserve argument boundaries.

Validation:
- uv lock
- UV_CACHE_DIR=.uv-cache uv run pytest --no-cov tests/test_vm_guest.py tests/test_vm_manager.py tests/test_cli.py tests/test_api.py tests/test_server.py tests/test_public_contract.py
- UV_CACHE_DIR=.uv-cache make check
- UV_CACHE_DIR=.uv-cache make dist-check
- real guest-backed smoke: task create --source-path, task exec -- cat note.txt, task delete

src/pyro_mcp/runtime_bundle/linux-x86_64/manifest.json

@@ -18,14 +18,14 @@
   "component_versions": {
     "base_distro": "debian-bookworm-20250210",
     "firecracker": "1.12.1",
-    "guest_agent": "0.1.0-dev",
+    "guest_agent": "0.2.0-dev",
     "jailer": "1.12.1",
     "kernel": "5.10.210"
   },
   "guest": {
     "agent": {
       "path": "guest/pyro_guest_agent.py",
-      "sha256": "65bf8a9a57ffd7321463537e598c4b30f0a13046cbd4538f1b65bc351da5d3c0"
+      "sha256": "3b684b1b07745fc7788e560b0bdd0c0535c31c395ff87474ae9e114f4489726d"
     }
   },
   "platform": "linux-x86_64",