fix: make 'run' output honest on non-TTY and under --keep-going

[andrewbudge]

Two related visibility fixes for oxo-flow run:

Non-TTY runs no longer go silent. Per-rule status was reported only through the indicatif progress bar, which auto-hides when stderr isn't a terminal — so pipes, redirects, nohup, CI, and schedulers showed nothing between the DAG listing and the final summary.

• Detect non-terminal stderr and fall back to plain log lines: Running: [i/n] <rule>, ✓ <rule> (Xs), and skip lines
• Interactive runs are untouched — the progress bar still owns the live display

--keep-going no longer hides failures. It swallowed executor errors outright and printed only a failure count.

• Collect failures and print a consolidated Failed rules: summary (rule name + concise reason) at the end
• Surface the previously-silent executor-error path

Tests: adds an integration test for the non-TTY fallback; tightens the keep-going test to assert the summary names the failed rule. make ci passes locally.

[ShixiangWang]

Thanks for so quick response and PR:)

[andrewbudge]

Of course! I will be working the silent failure memory bug next (should also be a relatively quick fix). Then I can focus on finishing the port of the phage pipline and continue testing. I have some thoughts on how to manage and bundle workflows with external scripts and environments, but I will write that up more formally later and share that.