Add persistent workspace shell sessions

Let agents inhabit a workspace across separate calls instead of only submitting one-shot execs.

Add workspace shell open/read/write/signal/close across the CLI, Python SDK, and MCP server, with persisted shell records, a local PTY-backed mock implementation, and guest-agent support for real Firecracker workspaces.

Mark the 2.5.0 roadmap milestone done, refresh docs/examples and the release metadata, and verify with uv lock, UV_CACHE_DIR=.uv-cache make check, and UV_CACHE_DIR=.uv-cache make dist-check.

docs/integrations.md

@@ -31,6 +31,7 @@ Recommended surface:
 
 - `vm_run`
 - `workspace_create(seed_path=...)` + `workspace_sync_push` + `workspace_exec` when the agent needs persistent workspace state
+- `open_shell` / `read_shell` / `write_shell` when the agent needs an interactive PTY inside that workspace
 
 Canonical example:
 
@@ -66,6 +67,7 @@ Recommended default:
 
 - `Pyro.run_in_vm(...)`
 - `Pyro.create_workspace(seed_path=...)` + `Pyro.push_workspace_sync(...)` + `Pyro.exec_workspace(...)` when repeated workspace commands are required
+- `Pyro.open_shell(...)` + `Pyro.write_shell(...)` + `Pyro.read_shell(...)` when the agent needs an interactive PTY inside the workspace
 
 Lifecycle note:
 
@@ -76,12 +78,14 @@ Lifecycle note:
   `/workspace` that starts from host content
 - use `push_workspace_sync(...)` when later host-side changes need to be imported into that
   running workspace without recreating it
+- use `open_shell(...)` when the agent needs interactive shell state instead of one-shot execs
 
 Examples:
 
 - [examples/python_run.py](../examples/python_run.py)
 - [examples/python_lifecycle.py](../examples/python_lifecycle.py)
 - [examples/python_workspace.py](../examples/python_workspace.py)
+- [examples/python_shell.py](../examples/python_shell.py)
 
 ## Agent Framework Wrappers