Add Tickets domain for the voucher-based ticket shop (#8)

Reviewed-on: #8
Co-authored-by: Patrick Mueller <patrick@mueller-patrick.tech>
Co-committed-by: Patrick Mueller <patrick@mueller-patrick.tech>

sql/tickets/001_init.sql

@@ -0,0 +1,102 @@
+-- Nachklang e.V. Tickets module — initial schema for TICKETS_DB
+-- Apply manually against the TICKETS_DB database (separate from CALENDAR_DB
+-- and FEEDBACK_DB). See nachklang-tickets/docs/plan-ticket-shop.md for the
+-- full design rationale.
+--
+-- Apply with e.g.:
+--   mysql -h <DB_HOST> -u <DB_USER> -p <TICKETS_DB> < 001_init.sql
+--
+-- Deliberately no USE statement here: the target database is selected via
+-- the mysql command line above (whatever TICKETS_DB is actually named in
+-- .env), not hardcoded to a literal schema name.
+--
+-- `event_id` columns below refer to Calendar's `events.event_id` (a
+-- different database). Deliberately no cross-database foreign key —
+-- Tickets reads Calendar events via events.service.ts in the same Node
+-- process, not via a DB-level join.
+
+-- 1. voucher_codes --------------------------------------------------------
+CREATE TABLE voucher_codes (
+    code             VARCHAR(12)  NOT NULL PRIMARY KEY,
+    status           ENUM('UNUSED','REDEEMED','VOID') NOT NULL DEFAULT 'UNUSED',
+    max_guests       INT          NOT NULL DEFAULT 2,
+    prefill_name     VARCHAR(255) NULL,
+    prefill_email    VARCHAR(255) NULL,
+    batch_id         VARCHAR(36)  NULL,
+    created_by_email VARCHAR(255) NOT NULL,
+    created_at       DATETIME     NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    KEY idx_vc_batch (batch_id),
+    KEY idx_vc_status (status)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
+
+-- 2. voucher_code_events (join: which concerts a code may be redeemed for) -
+CREATE TABLE voucher_code_events (
+    voucher_code_event_id INT AUTO_INCREMENT PRIMARY KEY,
+    code                   VARCHAR(12) NOT NULL,
+    event_id               INT         NOT NULL,
+    CONSTRAINT fk_vce_code FOREIGN KEY (code) REFERENCES voucher_codes(code) ON DELETE CASCADE,
+    UNIQUE KEY uq_vce_code_event (code, event_id),
+    KEY idx_vce_event (event_id)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
+
+-- 3. event_ticket_settings (per-concert voucher config) ---------------------
+-- One row per Calendar event_id that has ever had voucher settings
+-- configured. Absent row == uncapped, no deadline, address not collected
+-- (see docs/plan-ticket-shop.md — "absence over sentinels").
+CREATE TABLE event_ticket_settings (
+    event_id             INT        NOT NULL PRIMARY KEY,
+    capacity             INT        NULL,
+    redemption_deadline  DATETIME   NULL,
+    collect_address      TINYINT(1) NOT NULL DEFAULT 0,
+    updated_at           DATETIME   NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
+
+-- 4. redemptions ------------------------------------------------------------
+-- `status` is soft-state rather than a hard delete on undo, so guest data
+-- and history survive an undo for the audit trail. Capacity/reporting
+-- queries filter status = 'ACTIVE'. A code that gets redeemed again after
+-- being undone creates a new row here rather than reviving the old one.
+CREATE TABLE redemptions (
+    redemption_id   INT AUTO_INCREMENT PRIMARY KEY,
+    code            VARCHAR(12)  NOT NULL,
+    event_id        INT          NOT NULL,
+    status          ENUM('ACTIVE','UNDONE') NOT NULL DEFAULT 'ACTIVE',
+    contact_name    VARCHAR(255) NOT NULL,
+    contact_email   VARCHAR(255) NOT NULL,
+    contact_address TEXT         NULL,
+    guest_count     INT          NOT NULL,
+    redeemed_at     DATETIME     NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    CONSTRAINT fk_red_code FOREIGN KEY (code) REFERENCES voucher_codes(code),
+    KEY idx_red_event_status (event_id, status),
+    KEY idx_red_code (code)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
+
+-- 5. redemption_guests --------------------------------------------------------
+-- One row per attendee, including the primary contact (position 0).
+CREATE TABLE redemption_guests (
+    redemption_guest_id INT AUTO_INCREMENT PRIMARY KEY,
+    redemption_id       INT          NOT NULL,
+    name                VARCHAR(255) NOT NULL,
+    position            INT          NOT NULL DEFAULT 0,
+    CONSTRAINT fk_rg_redemption FOREIGN KEY (redemption_id) REFERENCES redemptions(redemption_id) ON DELETE CASCADE,
+    KEY idx_rg_redemption (redemption_id, position)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
+
+-- 6. voucher_audit_log ----------------------------------------------------
+-- Lightweight admin-action history per code (not a full version-history
+-- system) — who did what and why. Covers EDIT/VOID/UNDO only; the guest's
+-- own redemption isn't an admin action so it isn't logged here (it's
+-- already timestamped on `redemptions.redeemed_at`).
+CREATE TABLE voucher_audit_log (
+    audit_id        INT AUTO_INCREMENT PRIMARY KEY,
+    code            VARCHAR(12)  NOT NULL,
+    redemption_id   INT          NULL,
+    admin_email     VARCHAR(255) NOT NULL,
+    action          ENUM('EDIT','VOID','UNDO') NOT NULL,
+    change_summary  JSON         NULL,
+    reason          VARCHAR(500) NULL,
+    created_at      DATETIME     NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    CONSTRAINT fk_val_code FOREIGN KEY (code) REFERENCES voucher_codes(code) ON DELETE CASCADE,
+    CONSTRAINT fk_val_redemption FOREIGN KEY (redemption_id) REFERENCES redemptions(redemption_id) ON DELETE SET NULL,
+    KEY idx_val_code_time (code, created_at)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;