feat: initialize project backend structure and document system specifications across all modules

docs/specs/reward_campaign/campaign_rule_contributor.md

@@ -0,0 +1,35 @@
+---
+title: "Campaign Rule - Contributor Settings"
+type: OpenSpec
+status: Draft
+domain: Reward Campaign Management
+---
+
+# Campaign Rule - Contributor Settings
+
+## Requirement Definition
+Configures funding contributors for a reward. If a reward is funded by entities other than the transacting merchant (or split between them), Contributors define the split percentage.
+
+## Process Flow
+
+### Pre-Conditions
+- Rule must be created.
+- Contributing merchants (Chains) must exist in OLS.
+
+## Business Rules
+
+### Data Schema
+
+| Field Name | Description | Logic Type | Constraints / Rules |
+|---|---|---|---|
+| Contributor | The Chain funding the reward. | Enum (Lookup) | Required. Unique per rule. |
+| Contributor Percentage | Percentage of cost to fund. | Decimal | Required. > 0. |
+| Absorb Remainder | Absorbs rounding remainders. | Boolean | Required. Exactly one must be true. |
+
+### Execution
+- Total contribution must equal 100%.
+- Transaction processing splits the awarded value across Contributors based on percentages.
+- If no contributors are configured, the transacting Merchant (Chain) absorbs 100% of the cost.
+
+## Exception Flow
+- Validation failures block saving.