feat(devcontainer): add lazy activation and lifecycle management

Implemented lazy container activation for devcontainer-instance resources
with ContainerLifecycleState enum tracking six states (inactive, starting,
active, stopping, stopped, error) with validated transitions. Extended
DevcontainerHandler with devcontainer up CLI integration and JSON output
parsing for container start. Added periodic health checking via
devcontainer exec ping with configurable interval. Added agents resource
stop and agents resource rebuild CLI commands for manual lifecycle
control. Wired session close and plan completion hooks to automatic
container cleanup. Includes lifecycle state persistence in resource
registry with timestamped transitions. Added Behave BDD tests, Robot
integration tests, and ASV activation latency benchmarks.

- Added remoteWorkspaceFolder absolute-path validation
- Aligned spec: handler name, rebuild types, --yes flag on stop/rebuild
- Added registry re-read in stop_container success path for consistency
- Added session_id field to ContainerLifecycleTracker for scoped cleanup
- Scoped stop_all_active_containers to session_id when provided
- Wired _cleanup_devcontainers into fail_apply and fail_execute
- Wired start_health_check into activate_container success path
- Restructured facade session close to always run container cleanup
  even without session service (F4)
- Re-read tracker from registry in activate_container success path
- Added evict_terminal_trackers to cap registry growth
- Updated devcontainer_resources.md: health check auto-start, scoped
  cleanup hooks, known limitations for eviction and sandbox_strategy
- Wired evict_terminal_trackers into stop_all_active_containers so
  terminal-state trackers are actually evicted in production
- Made stop_container idempotent: returns early when container is
  already in a terminal state instead of raising ValueError
- Fixed benchmark health check thread leak in TimeActivationLatency
  by clearing registry after each timing loop
- Added rebuild pass-through (--reset-container flag to devcontainer up)
- Added host_workspace_path field on ContainerLifecycleTracker so
  health probes use the host-side path for devcontainer exec
- Wired lazy activation into DevcontainerHandler.resolve() for
  devcontainer-instance resources in non-running states
- Changed _default_strategy from SNAPSHOT to NONE (container
  itself provides isolation; SandboxFactory raises NotImplementedError
  for snapshot)
- Restricted _STOPPABLE_TYPES to devcontainer-instance only
  (container-instance is not directly stoppable via CLI)

ISSUES CLOSED: #514

robot/devcontainer_lifecycle.robot

@@ -0,0 +1,89 @@
+*** Settings ***
+Documentation    Integration tests for devcontainer lifecycle management (issue #514)
+Resource         ${CURDIR}/common.resource
+Suite Setup      Setup Test Environment
+Suite Teardown   Cleanup Test Environment
+
+*** Variables ***
+${HELPER}    ${CURDIR}/helper_devcontainer_lifecycle.py
+
+*** Test Cases ***
+ContainerLifecycleState Enum Values
+    [Documentation]    Verify all six lifecycle states exist
+    ${result}=    Run Process    ${PYTHON}    ${HELPER}    enum-values    cwd=${WORKSPACE}
+    Log    ${result.stdout}
+    Log    ${result.stderr}
+    Should Be Equal As Integers    ${result.rc}    0
+    Should Contain    ${result.stdout}    enum-values-ok
+
+Valid Transition Detected To Building
+    [Documentation]    Verify detected->building transition
+    ${result}=    Run Process    ${PYTHON}    ${HELPER}    transition-valid    cwd=${WORKSPACE}
+    Log    ${result.stdout}
+    Log    ${result.stderr}
+    Should Be Equal As Integers    ${result.rc}    0
+    Should Contain    ${result.stdout}    transition-valid-ok
+
+Invalid Transition Rejected
+    [Documentation]    Verify invalid transitions raise ValueError
+    ${result}=    Run Process    ${PYTHON}    ${HELPER}    transition-invalid    cwd=${WORKSPACE}
+    Log    ${result.stdout}
+    Log    ${result.stderr}
+    Should Be Equal As Integers    ${result.rc}    0
+    Should Contain    ${result.stdout}    transition-invalid-ok
+
+Lazy Activation With Mock Runner
+    [Documentation]    Verify lazy activation with mock devcontainer CLI
+    ${result}=    Run Process    ${PYTHON}    ${HELPER}    lazy-activation    cwd=${WORKSPACE}
+    Log    ${result.stdout}
+    Log    ${result.stderr}
+    Should Be Equal As Integers    ${result.rc}    0
+    Should Contain    ${result.stdout}    lazy-activation-ok
+
+Stop Container With Mock Runner
+    [Documentation]    Verify stop transitions active to stopped
+    ${result}=    Run Process    ${PYTHON}    ${HELPER}    stop-container    cwd=${WORKSPACE}
+    Log    ${result.stdout}
+    Log    ${result.stderr}
+    Should Be Equal As Integers    ${result.rc}    0
+    Should Contain    ${result.stdout}    stop-container-ok
+
+Rebuild Container With Mock Runner
+    [Documentation]    Verify rebuild transitions stopped to active
+    ${result}=    Run Process    ${PYTHON}    ${HELPER}    rebuild-container    cwd=${WORKSPACE}
+    Log    ${result.stdout}
+    Log    ${result.stderr}
+    Should Be Equal As Integers    ${result.rc}    0
+    Should Contain    ${result.stdout}    rebuild-container-ok
+
+Session Cleanup Stops Active Containers
+    [Documentation]    Verify session cleanup stops all active containers
+    ${result}=    Run Process    ${PYTHON}    ${HELPER}    session-cleanup    cwd=${WORKSPACE}
+    Log    ${result.stdout}
+    Log    ${result.stderr}
+    Should Be Equal As Integers    ${result.rc}    0
+    Should Contain    ${result.stdout}    session-cleanup-ok
+
+JSON Output Parsing
+    [Documentation]    Verify devcontainer up JSON output parsing
+    ${result}=    Run Process    ${PYTHON}    ${HELPER}    json-parsing    cwd=${WORKSPACE}
+    Log    ${result.stdout}
+    Log    ${result.stderr}
+    Should Be Equal As Integers    ${result.rc}    0
+    Should Contain    ${result.stdout}    json-parsing-ok
+
+Lifecycle Registry Persistence
+    [Documentation]    Verify tracker persists in registry
+    ${result}=    Run Process    ${PYTHON}    ${HELPER}    registry-persist    cwd=${WORKSPACE}
+    Log    ${result.stdout}
+    Log    ${result.stderr}
+    Should Be Equal As Integers    ${result.rc}    0
+    Should Contain    ${result.stdout}    registry-persist-ok
+
+CleanupService Has Devcontainer Method
+    [Documentation]    Verify CleanupService.stop_active_devcontainers exists
+    ${result}=    Run Process    ${PYTHON}    ${HELPER}    cleanup-method    cwd=${WORKSPACE}
+    Log    ${result.stdout}
+    Log    ${result.stderr}
+    Should Be Equal As Integers    ${result.rc}    0
+    Should Contain    ${result.stdout}    cleanup-method-ok