Two changes to the Run-page character/environment generation:

1. Generate FROM SCRATCH via the text model instead of the built-in static pool.
   stage_characters/stage_environments always iterated FIGHTER_POOL/
   ENVIRONMENT_POOL and used their hardcoded (pre-fallback) prompts — the LLM was
   never invoked for a full run. New _invent_profiles() calls the text model
   (_autogen_profile_payload) to invent fresh profiles; the static pool is only a
   fallback when no text model is configured (with a clear warning).

2. Phase the pipeline: invent ALL prompts first, then render ALL reference images,
   then train image LoRAs, then video LoRAs (prompts → images → image-LoRA →
   video-LoRA). New _render_profile_images() does the image phase from the saved
   prompts; the reuse/skip paths are unchanged. num_fighters/num_environments set
   how many to invent (default: the pool size).

(CLI main() still uses the pool-based stage_characters/stage_environments; the
web Run page is the phased-from-scratch path.)
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RdMufYvtTbtGDWsiZVoXce