feat: add prescription refills column to planner table and email (#207)

- Add 6th column 'Prescription refills' to frontend Planner table
- Add matching column to backend planner email (HTML + plaintext)
- Show remaining refills for meds with prescription tracking, '–' otherwise
- Add backend translations for new column header (EN + DE)
- Add frontend i18n keys for prescription refills column
- Update planner tests with medications table schema

Closes #203

backend/src/test/planner.test.ts

@@ -86,6 +86,39 @@ async function createSchema(client: Client) {
       is_active integer NOT NULL DEFAULT 1,
       created_at integer NOT NULL DEFAULT (strftime('%s','now')),
       updated_at integer NOT NULL DEFAULT (strftime('%s','now'))
+    )`,
+		`CREATE TABLE IF NOT EXISTS medications (
+      id integer PRIMARY KEY AUTOINCREMENT,
+      user_id integer NOT NULL,
+      name text NOT NULL,
+      generic_name text,
+      taken_by_json text NOT NULL DEFAULT '[]',
+      package_type text NOT NULL DEFAULT 'blister',
+      pack_count integer NOT NULL DEFAULT 1,
+      blisters_per_pack integer NOT NULL DEFAULT 1,
+      pills_per_blister integer NOT NULL DEFAULT 1,
+      total_pills integer,
+      loose_tablets integer NOT NULL DEFAULT 0,
+      stock_adjustment integer NOT NULL DEFAULT 0,
+      last_stock_correction_at integer,
+      pill_weight_mg integer,
+      dose_unit text DEFAULT 'mg',
+      usage_json text NOT NULL DEFAULT '[]',
+      every_json text NOT NULL DEFAULT '[]',
+      start_json text NOT NULL DEFAULT '[]',
+      intakes_json text NOT NULL DEFAULT '[]',
+      image_url text,
+      expiry_date text,
+      notes text,
+      intake_reminders_enabled integer NOT NULL DEFAULT 0,
+      prescription_enabled integer NOT NULL DEFAULT 0,
+      prescription_authorized_refills integer,
+      prescription_remaining_refills integer,
+      prescription_low_refill_threshold integer NOT NULL DEFAULT 1,
+      prescription_expiry_date text,
+      dismissed_until text,
+      updated_at integer NOT NULL DEFAULT (strftime('%s','now')),
+      FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
     )`,
 		`CREATE TABLE IF NOT EXISTS user_settings (
       id integer PRIMARY KEY AUTOINCREMENT,