fix: reduce flaky tests by preventing container auto-removal and parallel --all interference

[kasc0206]

Summary

Fix 5 flaky tests identified during Release mode testing (892 tests, 887 pass, 5 flaky).

Root Cause Analysis

TestCLIStop (4 failures): doLongRun defaults to autoRemove: true (--rm flag).
When a container crashes between creation and inspect/stop, --rm auto-deletes it,
causing subsequent container inspect / container stop to fail with "container not found".

TestCLIRemove (3 failures): Tests use delete --all / delete --all --force,
which operate on ALL containers. When multiple tests run in parallel, they delete
each other's containers.

TestCLIProgressAuto (1 failure): testExplicitAnsiProgress expects ANSI escape
sequences on stderr, but ANSI output is only emitted when stderr is a TTY. When
running with output redirected (CI, swift test > file), progress falls back to plain text.

Changes

File	Change
TestCLIStop.swift	4 tests: doLongRun(name:) → doLongRun(name:, autoRemove: false)
TestCLIRemove.swift	delete --all → delete <specific-names> to avoid cross-test interference
TestCLIRemove.swift	delete --all --force → delete --force <name>
TestCLIProgressAuto.swift	Guard ANSI assertion with isatty(STDERR_FILENO) check

Test Results (Release mode, before fix)

✘ Test run with 892 tests in 109 suites failed after 1430.181 seconds with 5 issues.

✘ Test testStopIdempotent() failed — container inspect failed: exit 1
✘ Test testDeleteAllSkipsRunning() failed — container inspect failed: exit 1
✘ Test testStopWithExplicitSignal() failed — container inspect failed: exit 1
✘ Test testStopWithoutSignal() failed — container inspect failed: exit 1
✘ Test testExplicitAnsiProgress() failed — expected ansi progress output on stderr