Initial HerbAPI implementation

Rust/Axum REST API (herbapi-api) with PostgreSQL, S3/Garage, OIDC auth.
Dioxus 0.7 WASM frontend (herbapi-ui) with sidebar layout and botanical reference style.
9 SQL migrations covering families, species, cultivars, suppliers, companions, images, users, API tokens.

herbapi-api/migrations/008_create_users.sql

@@ -0,0 +1,15 @@
+CREATE TABLE IF NOT EXISTS users (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    email VARCHAR NOT NULL,
+    name VARCHAR,
+    nickname VARCHAR,
+    avatar_url VARCHAR,
+    provider VARCHAR NOT NULL DEFAULT 'authentik',
+    provider_id VARCHAR,
+    admin BOOLEAN NOT NULL DEFAULT FALSE,
+    inserted_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE UNIQUE INDEX IF NOT EXISTS users_email_index ON users (email);
+CREATE UNIQUE INDEX IF NOT EXISTS users_provider_provider_id_index ON users (provider, provider_id);