Update spec and readme

backend/spec/main.md

@@ -1,9 +1,17 @@
 # `async fn main() -> Result<()>`
 
-- Configures logging
-- Calls `create_pool` to get a `SqlitePool`, then creates `Query`, `Command`, `Robot`, `Billing`, `Api`, and `Infra`
-- Get an axum router from `api.router`
-- Adds CORS middleware based on `origins`
-- Calls `axum::serve` with a listener
-- Spawns `infra.start`
-- Spawns `billing.start`
+- Loads `.env` (via `dotenvy`) and configures tracing/logging from the default env filter
+- Calls `Env::load()` to read and validate all configuration
+- Calls `create_pool(&env.database_url)` to get a `SqlitePool`
+- Constructs the services, passing `&env` where needed:
+  - `Robot::new(&env).await` (publishes the robot's nostr identity)
+  - `Stripe::new(&env)`
+  - `Query::new(pool.clone(), &env)`
+  - `Command::new(pool)`
+  - `Billing::new(query.clone(), command.clone(), &env)`
+  - `Infra::new(query.clone(), command.clone(), &env)`
+  - `Api::new(query, command, billing.clone(), stripe, robot, infra.clone(), &env)`
+- Builds a CORS layer restricted to the parsed `env.server_allow_origins`
+- Gets the axum router from `api.router()` and applies the CORS layer
+- Spawns `infra.start()` and `billing.start()` as background tasks
+- Binds a `TcpListener` on `env.server_host:env.server_port` and calls `axum::serve`