Adversary creator: Stats step with inline balance range bars

[gwillish]

Second step of the adversary creator. The GM enters numeric stats with inline visual feedback showing where each value sits relative to SRD expectations for the chosen type and tier.

Scope

• Fields: HP (max), Stress (max), Difficulty, Threshold Major, Threshold Severe, Attack modifier
• Inline range bar or indicator next to each field: shows "within range / above average / outlier" relative to the type+tier expected range
• Feedback is advisory only — no values are blocked or prevented (Principle 8)
• "Back" returns to Identity step; "Next" advances to Attacks + Features

Depends on

• Identity step (Adversary creator: Identity step (name, type, tier, expected stat ranges) #41) — needs type and tier to compute expected ranges

Acceptance criteria

• All stat fields present
• Range indicators update as the GM types
• Out-of-range values show a visual indicator, not an error
• Stats carry forward to next step