Add public/private calendars, full iCal support, and iCal URL import

- Public/private: toggle is_public via PUT /calendars/{id}; generate/clear
  public_token and return ical_url when public
- Public feed: GET /cal/{token}/feed.ics (no auth) for subscription in
  Google/Apple/Outlook calendars
- Full iCal export: use golang-ical; VALARM, ATTENDEE, all-day (VALUE=DATE),
  RRULE, DTSTAMP, CREATED, LAST-MODIFIED
- Full iCal import: parse TZID, VALUE=DATE, VALARM, ATTENDEE, RRULE
- Import from URL: POST /calendars/import-url with calendar_id + url
- Migration: unique index on public_token, calendar_subscriptions table
- Config: BASE_URL for ical_url; Calendar model + API: ical_url field
- Docs: OpenAPI, llms.txt, README, SKILL.md, about/overview

Made-with: Cursor

internal/config/config.go

@@ -12,17 +12,20 @@ type Config struct {
 	RedisAddr   string
 	ServerPort  string
 	Env         string
+	BaseURL     string
 }
 
 func Load() *Config {
 	loadEnvFile(".env")
 
+	port := getEnv("SERVER_PORT", "8080")
 	return &Config{
 		DatabaseURL: getEnv("DATABASE_URL", "postgres://postgres:postgres@localhost:5432/calendarapi?sslmode=disable"),
 		JWTSecret:   getEnv("JWT_SECRET", "dev-secret-change-me"),
 		RedisAddr:   os.Getenv("REDIS_ADDR"),
-		ServerPort:  getEnv("SERVER_PORT", "8080"),
+		ServerPort:  port,
 		Env:         getEnv("ENV", "development"),
+		BaseURL:     getEnv("BASE_URL", "http://localhost:"+port),
 	}
 }