[Partner Nodes] replace NanoBanana2 node with new node that uses Autogrow

[bigcat88]

Regarding changes in the app/node_replace_manager.py file:

We should skip input_mapping entries whose old_id is absent from the prompt.

apply_replacements reassigns inputs by indexing node_struct["inputs"][old_id] directly, which raises KeyError whenever the old node had an optional input that the workflow didn't connect as Core omits unconnected optional input slots from the prompt JSON.

This wasn't reachable before because every existing replacement (ImageBatch, ImageScaleBy) only maps required inputs, which are always present. The new GeminiNanoBanana2 -> GeminiNanoBanana2V2 replacement is the first to map optional slots (images, files) - text-to-image workflows, which leave both unconnected would crash without this guard.

API Node PR Checklist

Scope

• Is API Node Change

Pricing & Billing

• Need pricing update
• No pricing update

If Need pricing update:

• Metronome rate cards updated
• Auto‑billing tests updated and passing

QA

• QA done
• QA not required

Comms

• Informed Kosinkadink