fix: resolve go vet error and dayStart logic in ComputeDailyTotals

- Fix 'string(d)' int-to-rune conversion in rpg_test.go by using fmt.Sprintf
- Fix ComputeDailyTotals dayStart logic: initial state should be StateWorking
  when dayStart > 0, correctly counting work from dayStart to first out event
- Update README project structure to reflect new domain/handler/repo layout
- Implement missing achievements: rpg_pioneer (on RPG enable) and
  salary_setter (on first rate set)
- Add tryUnlockAchievement helper to Handler

internal/repo/migrations/001_init.sql

@@ -0,0 +1,59 @@
+-- +goose Up
+CREATE TABLE IF NOT EXISTS work_types (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    name TEXT NOT NULL UNIQUE,
+    created_at INTEGER NOT NULL DEFAULT (unixepoch())
+);
+
+INSERT OR IGNORE INTO work_types (id, name) VALUES (1, 'onsite');
+INSERT OR IGNORE INTO work_types (id, name) VALUES (2, 'remote');
+
+CREATE TABLE IF NOT EXISTS users (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    chat_id INTEGER NOT NULL UNIQUE,
+    timezone TEXT NOT NULL DEFAULT 'Asia/Tehran',
+    is_active INTEGER NOT NULL DEFAULT 1,
+    report_enabled INTEGER NOT NULL DEFAULT 1,
+    report_time TEXT NOT NULL DEFAULT '23:00',
+    last_report_date TEXT DEFAULT NULL,
+    export_accent TEXT NOT NULL DEFAULT 'ocean'
+        CHECK (export_accent IN ('ocean', 'beach', 'rose', 'catppuccin')),
+    calendar TEXT NOT NULL DEFAULT 'gregorian'
+        CHECK (calendar IN ('gregorian', 'jalali', 'hijri')),
+    created_at INTEGER NOT NULL DEFAULT (unixepoch()),
+    updated_at INTEGER NOT NULL DEFAULT (unixepoch())
+);
+
+CREATE TABLE IF NOT EXISTS days (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    user_id INTEGER NOT NULL REFERENCES users(id),
+    date TEXT NOT NULL CHECK (date = strftime('%Y-%m-%d', date)),
+    is_day_off INTEGER NOT NULL DEFAULT 0,
+    day_off_reason TEXT NOT NULL DEFAULT '',
+    current_work_type_id INTEGER NOT NULL DEFAULT 1 REFERENCES work_types(id),
+    min_break_threshold INTEGER NOT NULL DEFAULT 300,
+    created_at INTEGER NOT NULL DEFAULT (unixepoch()),
+    updated_at INTEGER NOT NULL DEFAULT (unixepoch()),
+    UNIQUE(user_id, date)
+);
+
+CREATE TABLE IF NOT EXISTS events (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    user_id INTEGER NOT NULL REFERENCES users(id),
+    day_id INTEGER NOT NULL REFERENCES days(id),
+    event_type TEXT NOT NULL CHECK (event_type IN ('in', 'out')),
+    work_type_id INTEGER REFERENCES work_types(id),
+    occurred_at INTEGER NOT NULL CHECK (occurred_at > 0),
+    note TEXT NOT NULL DEFAULT '',
+    created_at INTEGER NOT NULL DEFAULT (unixepoch())
+);
+
+CREATE INDEX IF NOT EXISTS idx_events_user_day ON events(user_id, day_id);
+CREATE INDEX IF NOT EXISTS idx_events_user_occurred ON events(user_id, occurred_at);
+CREATE INDEX IF NOT EXISTS idx_days_user_date ON days(user_id, date);
+
+-- +goose Down
+DROP TABLE IF EXISTS events;
+DROP TABLE IF EXISTS days;
+DROP TABLE IF EXISTS users;
+DROP TABLE IF EXISTS work_types;