feat(assets): build media assets one confirmed change per round - #44

What

Adds wisdom:assets (magic word build assets): an iterative builder for image, video and audio assets. Each round changes one thing against a fixed base and generates only after the round spec is confirmed.

• Loads $SESSION/ASSETS.global.lock and $SESSION/<set>_assets.lock first, when they exist.
• Settles the base, the frozen concepts, the one change, its scope and the candidate count (default 3), then stops once on the round spec.
• Generation goes to whatever MCP server or CLI the session has; with none, it outputs the spec and the prompt.
• A pick updates the lock and its history; candidates never enter a lock and are never deleted.
• This version is written against images; video and audio run the same loop with no media-specific fields.

Also lists the skill in both READMEs and bumps the plugin and marketplace to 3.1.0.

Checks

• make test: all 4 checks pass.
• wisdom:review: first round FAIL (the base of the next round was undefined), fixed; second round WARN with three low-severity ambiguities, all fixed afterwards. The final text was not reviewed a third time.
• The skill is prose and was not exercised against a real generation backend.

Closes #43

🤖 Generated with Claude Code