feat(batch): use Flow's native count selector for -n N; add --same-project for multi-prompt batches #14

Two related improvements

Part 1 — Fix -n N to use Flow's UI count selector (bug)

Today: gflow image t2i "prompt" -n 4 fans out 4 parallel single-image submissions into 4 separate projects. The asyncio.Lock in 1621748 made this safe, but the design is wrong.

Should be: Call generate_images(count=N) once. The transport sets the x{N} count button in Flow's UI (1x / x2 / x3 / x4), submits once, downloads N images from one project. Max -n 4 (Flow's UI cap). CLI rejects -n > 4 with a clear error.

Result: 1 project, N images, 1 submission round-trip. Strictly faster and matches user intent.

Part 2 — Add --same-project for multi-prompt batches (feature)

Today there's no first-class multi-prompt CLI (each prompt = separate gflow invocation). When that lands (e.g. gflow image batch manifest.tsv), users will want a choice:

• Default: each prompt → its own new project.
• --same-project: all prompts share one project, submitted sequentially with random 3-7s jitter. On per-item failure, log and continue.

Combines cleanly with Part 1: gflow image batch m.tsv -n 4 --same-project = one project, each manifest row produces 4 images via the native selector, 3-7s jitter between rows.

Implementation sketch

• Part 1: refactor generate_images_batch to delegate to generate_images(count=N) when given one prompt; remove the fan-out plus lock for that path (lock may still be needed for cross-profile concurrency — investigate). Add count-selector UI interaction. CLI validation: -n in [1, 4].
• Part 2: new --same-project flag on the multi-prompt commands (when those land). New transport path _run_batch_same_project(prompts, jitter_range).

Open

• Flag name --same-project confirmed (bikeshed: --group, --one-project).
• Jitter range: 3-7s hardcoded for v1, configurable later.

Out of scope

• Per-prompt -n (different counts per prompt) — future, behind a JSON manifest.
• Parallel-in-same-project — Flow's UI almost certainly can't handle it.