Edicts Slice 5: Multi-slot + rank tiers + duplicate-lever rule #515

Part of #510.

Scale from one slot to the full rank-gated loadout.

Scope

• Slot count derived from CivilizationMilestoneManager.GetCivilizationRank (1 at Nascent/Rising → 2 at Dominant/Hegemonic → 3 at Eternal).
• MinRank gates tier availability per edict.
• Duplicate-lever rule: SetEdict rejects activating an edict whose PrimaryLever matches an already-active edict. Global-favor and domain-favor are distinct levers and may coexist.
• UI reflects slot count and locked tiers.

Acceptance

• A civ can run up to its rank's slot count; over-cap activation rejected.
• Activating a second edict sharing a PrimaryLever is rejected with a clear message.

Depends on: Slice 4.