Add project scope documentation for AI playgroup registration system

Define complete non-technical scope for replacing Google Forms registration
with an AI-powered conversational agent. Includes:

- Registration data requirements (13 fields with validation rules)
- Knowledge base content (fees, regulations, schedule, FAQ from official PDFs)
- Conversation flow design with bilingual support (German/English)
- Agent personality guidelines (warm & friendly tone)
- Admin notification routing by playgroup type
- Email reminder system for incomplete registrations
- Data export formats (CSV/JSON)
- Channel configuration (email + chat)
- Release priorities (MVP scope defined)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

openspec/changes/define-project-scope/specs/registration-data-store/spec.md

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+## ADDED Requirements
+
+### Requirement: Store registrations in structured format
+The system SHALL store completed registration data in a structured, machine-readable format (e.g., JSON).
+
+#### Scenario: Registration saved
+- **WHEN** a registration is completed
+- **THEN** all collected data SHALL be stored in a structured format with consistent field names
+
+#### Scenario: Data structure consistency
+- **WHEN** multiple registrations are stored
+- **THEN** all records SHALL follow the same schema structure
+
+### Requirement: Registration schema validation
+The system SHALL validate registration data against a defined schema before storage.
+
+#### Scenario: Valid registration stored
+- **WHEN** a registration with all required fields is submitted
+- **THEN** the system SHALL validate and store the registration
+
+#### Scenario: Invalid registration rejected
+- **WHEN** a registration with missing or invalid fields is submitted for storage
+- **THEN** the system SHALL reject the storage and report the validation errors
+
+### Requirement: Registration data is exportable
+The system SHALL allow export of registration data in common formats for further processing.
+
+#### Scenario: Export to CSV
+- **WHEN** the admin requests a CSV export
+- **THEN** the system SHALL generate a CSV file with all registration records
+
+#### Scenario: Export to JSON
+- **WHEN** the admin requests a JSON export
+- **THEN** the system SHALL provide registration data in JSON format
+
+### Requirement: Registration records are queryable
+The system SHALL allow querying registrations by common criteria.
+
+#### Scenario: Query by date range
+- **WHEN** the admin queries registrations within a date range
+- **THEN** the system SHALL return matching registration records
+
+#### Scenario: Query by booking day
+- **WHEN** the admin queries registrations for a specific booking day
+- **THEN** the system SHALL return registrations that include that day
+
+### Requirement: Registration data includes metadata
+The system SHALL store metadata alongside registration data including submission timestamp and source channel.
+
+#### Scenario: Timestamp recorded
+- **WHEN** a registration is completed
+- **THEN** the record SHALL include the submission date and time
+
+#### Scenario: Channel recorded
+- **WHEN** a registration is completed via email or chat
+- **THEN** the record SHALL indicate which channel was used