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

docs/integrations.md

@@ -30,7 +30,7 @@ Best when:
 Recommended surface:
 
 - `vm_run`
-- `task_create` + `task_exec` when the agent needs persistent workspace state
+- `task_create(source_path=...)` + `task_exec` when the agent needs persistent workspace state
 
 Canonical example:
 
@@ -65,14 +65,15 @@ Best when:
 Recommended default:
 
 - `Pyro.run_in_vm(...)`
-- `Pyro.create_task(...)` + `Pyro.exec_task(...)` when repeated workspace commands are required
+- `Pyro.create_task(source_path=...)` + `Pyro.exec_task(...)` when repeated workspace commands are required
 
 Lifecycle note:
 
 - `Pyro.exec_vm(...)` runs one command and auto-cleans the VM afterward
 - use `create_vm(...)` + `start_vm(...)` only when you need pre-exec inspection or status before
   that final exec
-- use `create_task(...)` when the agent needs repeated commands in one persistent `/workspace`
+- use `create_task(source_path=...)` when the agent needs repeated commands in one persistent
+  `/workspace` that starts from host content
 
 Examples: