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

tests/test_public_contract.py

@@ -17,6 +17,7 @@ from pyro_mcp.contract import (
     PUBLIC_CLI_DEMO_SUBCOMMANDS,
     PUBLIC_CLI_ENV_SUBCOMMANDS,
     PUBLIC_CLI_RUN_FLAGS,
+    PUBLIC_CLI_TASK_CREATE_FLAGS,
     PUBLIC_CLI_TASK_SUBCOMMANDS,
     PUBLIC_MCP_TOOLS,
     PUBLIC_SDK_METHODS,
@@ -67,6 +68,11 @@ def test_public_cli_help_lists_commands_and_run_flags() -> None:
     task_help_text = _subparser_choice(parser, "task").format_help()
     for subcommand_name in PUBLIC_CLI_TASK_SUBCOMMANDS:
         assert subcommand_name in task_help_text
+    task_create_help_text = _subparser_choice(
+        _subparser_choice(parser, "task"), "create"
+    ).format_help()
+    for flag in PUBLIC_CLI_TASK_CREATE_FLAGS:
+        assert flag in task_create_help_text
 
     demo_help_text = _subparser_choice(parser, "demo").format_help()
     for subcommand_name in PUBLIC_CLI_DEMO_SUBCOMMANDS: