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

docs/specs/reward_campaign/cep_rule.md

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+---
+title: "Counter Extract & Process (CEP) Rule"
+type: OpenSpec
+status: Draft
+domain: Reward Campaign Management
+---
+
+# Counter Extract & Process (CEP) Rule
+
+## Requirement Definition
+Extracts values accumulated in a Counter at the end of a defined period and generates a transaction to trigger an Award/Redeem rule based on that accumulated total.
+
+## Process Flow
+
+### Pre-Conditions
+- Users must have access rights.
+- A Counter tracking the required metric must exist.
+
+## Business Rules
+
+### Data Schema
+
+#### General & Extraction Settings
+| Field Name | Description | Logic Type | Constraints / Rules |
+|---|---|---|---|
+| Rule Type | CEP. | Enum | Required. |
+| Counter to Extract | Counter containing the value. | Enum (Lookup) | Required. |
+| Bucket to Extract | Current, Previous, Period Before Last. | Enum | Required. |
+| Rule type to process | Rule type of the destination rule. | Enum (Lookup) | Required. |
+| Transaction Code | TC used to post the extracted transaction. | Enum (Lookup) | Required. |
+| -ve Bal. Adjust. TC | TC for negative extracted values. | Enum (Lookup) | Optional. |
+| Account with blocked Card | Include or Exclude blocked cards. | Boolean | Conditional (if Acct/Card entity). |
+| Run schedule | Day, Month, Annual, N days AOD, Stmt Cycle. | Enum (Lookup) | Required. Defines execution frequency. |
+
+### Execution
+- Evaluated by the CEP Batch scheduled at end-of-day.
+- The extracted Counter Bucket value becomes the `Amount A` for the destination Rule.
+- State of Counter Buckets is updated based on Counter Definition (e.g., closed after extraction) to prevent double-processing.
+
+## Exception Flow
+- N/A