Add chunk task status and chunk task watch for pipeline observability

[hidetaka-cci]

• Add chunk task status <pipeline-id> to fetch and display pipeline/workflow/job state once.
• Add chunk task watch <pipeline-id> to poll until workflows complete (--interval, --timeout).
• Print a CircleCI web URL after chunk task run when pipeline metadata is available.
• Extend the CircleCI client with GetPipeline, ListPipelineWorkflows, and ListWorkflowJobs.

Closes #

Motivation

Friction report 5-1 (task-run-status-observability.md): after chunk task run, users and agents had no CLI path to observe progress. The trigger path already authenticated to CircleCI; only status APIs and commands were missing.

Example

chunk task run --definition dev --prompt "Fix the flaky test"
# Run triggered: run-abc-123
# Pipeline:      pipeline-def-456
# URL:           https://app.circleci.com/pipelines/gh/org/repo/99/workflows/workflow-abc-789

chunk task status pipeline-def-456
# Pipeline:      pipeline-def-456
# Number:        99
# State:         created
# URL:           https://app.circleci.com/pipelines/gh/org/repo/99/workflows/workflow-abc-789
# Workflow:      chunk-task (running)

chunk task watch pipeline-def-456 --interval 5s --timeout 30m
# Polls until success or failure; exits non-zero on failure/timeout

Changes

Area	Change
internal/circleci/client.go, types.go	GetPipeline, ListPipelineWorkflows, ListWorkflowJobs
internal/task/status.go	FetchStatus, WatchStatus, RunWebURL, terminal detection
internal/cmd/task.go	task status, task watch; URL line on task run
internal/testing/fakes/circleci.go	Fake pipeline/workflow/job handlers
docs/CLI.md	Command tree + behavior notes
Tests	internal/circleci/pipeline_test.go, internal/task/status_test.go, acceptance/task_test.go

Out of scope

• chunk task logs
• Resolving status from run ID (no public agents GET in client today)
• TTY progress spinner or job log streaming

Test plan

• go test -race ./internal/task/... ./internal/circleci/... ./acceptance/ -run 'TestFetchStatus|TestWatchStatus|TestPipelineWebURL|TestWorkflowTerminal|TestGetPipeline|TestListPipeline|TestTaskStatus|TestTaskWatch|TestTaskRunIncludesURL'
• Unit: TestFetchStatus, TestFetchStatusNoWorkflows, TestWatchStatusSuccess, TestWatchStatusFailed, TestWatchStatusTimeout
• Client: TestGetPipeline, TestListPipelineWorkflows, TestListWorkflowJobs
• Acceptance: TestTaskStatus, TestTaskStatusJSON, TestTaskStatusMissingToken, TestTaskWatchSuccess, TestTaskWatchFailure, TestTaskRunIncludesURL