Add stopped-workspace disk export and inspection

Finish the 3.1.0 secondary disk-tools milestone so stable workspaces can be
stopped, inspected offline, exported as raw ext4 images, and started again
without changing the primary workspace-first interaction model.

Add workspace stop/start plus workspace disk export/list/read across the CLI,
SDK, and MCP, backed by a new offline debugfs inspection helper and guest-only
validation. Scrub runtime-only guest state before disk inspection/export, and
fix the real guest reliability gaps by flushing the filesystem on stop and
removing stale Firecracker socket files before restart.

Update the docs, examples, changelog, and roadmap to mark 3.1.0 done, and
cover the new lifecycle/disk paths with API, CLI, manager, contract, and
package-surface tests.

Validation: uv lock; UV_CACHE_DIR=.uv-cache make check; UV_CACHE_DIR=.uv-cache
make dist-check; real guest-backed smoke for create, shell/service activity,
stop, workspace disk list/read/export, start, exec, and delete.

CHANGELOG.md

@@ -2,6 +2,17 @@
 
 All notable user-visible changes to `pyro-mcp` are documented here.
 
+## 3.1.0
+
+- Added explicit workspace lifecycle stop/start operations across the CLI, Python SDK, and MCP
+  server so a persistent workspace can be paused and resumed without resetting `/workspace`,
+  snapshots, or command history.
+- Added secondary stopped-workspace disk tools with raw ext4 export plus offline `disk list` and
+  `disk read` inspection for guest-backed workspaces.
+- Scrubbed guest runtime-only paths such as `/run/pyro-secrets`, `/run/pyro-shells`, and
+  `/run/pyro-services` before stopped-workspace disk export and offline inspection so those tools
+  stay secondary to the stable workspace product without leaking runtime-only state.
+
 ## 3.0.0
 
 - Promoted the workspace-first product surface to stable across the CLI, Python SDK, and MCP