test(plan): TDD failing tests for checkpoint real rollback (bug #822)

TDD expected-fail tests proving bug #822 exists:
CheckpointService.rollback_to_checkpoint() returns a successful
RollbackResult but does not execute git reset --hard. Files modified
after the checkpoint remain unchanged after rollback.

Also fixes Robot Framework timeout robustness across the entire test
suite: all Run Process calls now use on_timeout=kill (prevents
SIGTERM-induced -15 exit codes under CI load) and timeouts increased
to 120s (prevents premature kills during heavy parallel execution).

ISSUES CLOSED: #839

robot/resource_cli.robot

@@ -16,7 +16,7 @@ Set Environment Variables
     Set Environment Variable    CLEVERAGENTS_TESTING_USE_MOCK_AI    true
     ${script}=    Set Variable    from cleveragents.infrastructure.database.models import Base; from sqlalchemy import create_engine; e \= create_engine("${DB_URL}"); Base.metadata.create_all(e)
     ${result}=    Run Process    ${PYTHON}    -c    ${script}
-    ...    env:PYTHONPATH=src    timeout=30s
+    ...    env:PYTHONPATH=src    timeout=120s    on_timeout=kill
     Should Be Equal As Integers    ${result.rc}    0
 
 Clean Up Test Database
@@ -27,7 +27,7 @@ Resource Type List Returns Output
     [Documentation]    Verify resource type list command runs without error
     ${result}=    Run Process    ${PYTHON}    -m    cleveragents    resource    type    list
     ...    env:PYTHONPATH=src    env:CLEVERAGENTS_DATABASE_URL=${DB_URL}    env:CLEVERAGENTS_TESTING_USE_MOCK_AI=true
-    ...    timeout=30s    stderr=STDOUT
+    ...    timeout=120s    on_timeout=kill    stderr=STDOUT
     Log    ${result.stdout}
     Should Be Equal As Integers    ${result.rc}    0
 
@@ -35,6 +35,6 @@ Resource Show Non Existent Returns Error
     [Documentation]    Verify resource show for non-existent resource fails gracefully
     ${result}=    Run Process    ${PYTHON}    -m    cleveragents    resource    show    nonexistent
     ...    env:PYTHONPATH=src    env:CLEVERAGENTS_DATABASE_URL=${DB_URL}    env:CLEVERAGENTS_TESTING_USE_MOCK_AI=true
-    ...    timeout=30s    stderr=STDOUT
+    ...    timeout=120s    on_timeout=kill    stderr=STDOUT
     Log    ${result.stdout}
     Should Not Be Equal As Integers    ${result.rc}    0