Scenario strategic identity (not only numeric modifiers) #98

Context

Scenarios ship in data/scenarios.json (#62) with starting resources and modifiers (e.g. Dust Season event gate, Silent Colony requiresBuilding). Game-design review: avoid a single dominant build order (hydro + solar L3) across all scenarios; each scenario should imply a different viable strategy, not only ±resources.

Related: Epic #79, gameplay-depth-plan.md, balance.md (CI stays on Standard run).

Problem

Players who learn one opening solve every profile.

Proposal

For each non-standard scenario, document and implement one situational advantage that rewards a distinct build or pacing choice:

Use existing levers: modifiers, event requiresBuilding / weight, dailyEffects, building modifiers—not Go-only switches unless eligibility needs it.

Acceptance criteria

• Design note in PR (or docs/balance.md § Scenarios): intended “good” opener per scenario in 2–3 sentences each.
• At least two non-standard scenarios have a baseline or simulate script that differs materially from scripts/conservative.json opener (new script or extended script OK).
• Standard run baselines unchanged unless intentional (TDD: failing baseline → tune → update baseline.go).
• go test ./internal/game/ -run TestBalanceBaseline passes.

Out of scope

• New scenario IDs beyond the five already planned.
• PvP / leaderboard balance.

Agent notes

• RED: add/adjust baseline or TestEarlyBalance_* assertion for one scenario-specific script before tuning JSON.
• Terminology: Scenario, Standard run, Event eligibility per CONTEXT.md.