Add task sync push milestone

Tasks could start from host content in 2.2.0, but there was still no post-create path to update a live workspace from the host. This change adds the next host-to-task step so repeated fix or review loops do not require recreating the task for every local change.

Add task sync push across the CLI, Python SDK, and MCP server, reusing the existing safe archive import path from seeded task creation instead of introducing a second transfer stack. The implementation keeps sync separate from workspace_seed metadata, validates destinations under /workspace, and documents the current non-atomic recovery path as delete-and-recreate.

Validation:
- uv lock
- UV_CACHE_DIR=.uv-cache uv run pytest --no-cov tests/test_cli.py tests/test_vm_manager.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 sync push, task exec to verify both files, task delete

tests/test_public_contract.py

@@ -19,6 +19,8 @@ from pyro_mcp.contract import (
     PUBLIC_CLI_RUN_FLAGS,
     PUBLIC_CLI_TASK_CREATE_FLAGS,
     PUBLIC_CLI_TASK_SUBCOMMANDS,
+    PUBLIC_CLI_TASK_SYNC_PUSH_FLAGS,
+    PUBLIC_CLI_TASK_SYNC_SUBCOMMANDS,
     PUBLIC_MCP_TOOLS,
     PUBLIC_SDK_METHODS,
 )
@@ -73,6 +75,14 @@ def test_public_cli_help_lists_commands_and_run_flags() -> None:
     ).format_help()
     for flag in PUBLIC_CLI_TASK_CREATE_FLAGS:
         assert flag in task_create_help_text
+    task_sync_help_text = _subparser_choice(_subparser_choice(parser, "task"), "sync").format_help()
+    for subcommand_name in PUBLIC_CLI_TASK_SYNC_SUBCOMMANDS:
+        assert subcommand_name in task_sync_help_text
+    task_sync_push_help_text = _subparser_choice(
+        _subparser_choice(_subparser_choice(parser, "task"), "sync"), "push"
+    ).format_help()
+    for flag in PUBLIC_CLI_TASK_SYNC_PUSH_FLAGS:
+        assert flag in task_sync_push_help_text
 
     demo_help_text = _subparser_choice(parser, "demo").format_help()
     for subcommand_name in PUBLIC_CLI_DEMO_SUBCOMMANDS: