WP-00: project skeleton with three-level test harness

Cargo workspace (domain, application, infrastructure, api), axum health endpoint
with SPA fallback, Vue 3 + Tailwind frontend, Vitest, Playwright, Makefile,
Gitea Actions CI and README.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

backend/crates/api/src/config.rs

@@ -0,0 +1,35 @@
+//! Runtime configuration read from environment variables (see `.env.example`).
+use std::net::SocketAddr;
+
+#[derive(Clone, Debug)]
+pub struct Config {
+    pub database_url: String,
+    pub jwt_secret: String,
+    pub bind: SocketAddr,
+    pub bootstrap_admin: Option<(String, String)>,
+    pub cookie_secure: bool,
+    pub frontend_dir: String,
+}
+
+impl Config {
+    pub fn from_env() -> anyhow::Result<Self> {
+        let env = |k: &str| std::env::var(k).ok().filter(|v| !v.is_empty());
+        let jwt_secret =
+            env("JWT_SECRET").ok_or_else(|| anyhow::anyhow!("JWT_SECRET is required"))?;
+        anyhow::ensure!(
+            jwt_secret.len() >= 32,
+            "JWT_SECRET must be at least 32 characters"
+        );
+        Ok(Self {
+            database_url: env("DATABASE_URL")
+                .unwrap_or_else(|| "sqlite://data/monitoring.db?mode=rwc".into()),
+            jwt_secret,
+            bind: env("BIND")
+                .unwrap_or_else(|| "127.0.0.1:8080".into())
+                .parse()?,
+            bootstrap_admin: env("BOOTSTRAP_ADMIN_EMAIL").zip(env("BOOTSTRAP_ADMIN_PASSWORD")),
+            cookie_secure: env("COOKIE_SECURE").is_some_and(|v| v == "true" || v == "1"),
+            frontend_dir: env("FRONTEND_DIR").unwrap_or_else(|| "../frontend/dist".into()),
+        })
+    }
+}