docs: rewrite README with structured overview and quick start guide

Replaces the minimal project description with a comprehensive README
including a component overview table, quick start instructions, common
Ansible operations, and links to detailed documentation. Aligns with
Red Panda Approval™ standards.

terraform/outputs.tf

@@ -0,0 +1,38 @@
+output "uranian_hosts" {
+  description = "Information about Uranian host containers"
+  value = {
+    for name, instance in incus_instance.uranian_hosts : name => {
+      name           = instance.name
+      ipv4           = instance.ipv4_address
+      description    = local.uranian_hosts[name].description
+      role           = local.uranian_hosts[name].role
+      security_nesting = lookup(local.uranian_hosts[name].config, "security.nesting", false)
+    }
+  }
+}
+
+output "project_info" {
+  description = "Agathos project information"
+  value = {
+    name        = incus_project.agathos.name
+    description = incus_project.agathos.description
+  }
+}
+
+output "agathos_inventory" {
+  description = "Host inventory for documentation (sandbox.html) and DHCP/DNS provisioning reference"
+  value = {
+    uranian_hosts = {
+      hosts = {
+        for name, instance in incus_instance.uranian_hosts : name => {
+          name             = instance.name
+          ipv4             = instance.ipv4_address
+          role             = local.uranian_hosts[name].role
+          description      = local.uranian_hosts[name].description
+          image            = local.uranian_hosts[name].image
+          security_nesting = lookup(local.uranian_hosts[name].config, "security.nesting", false)
+        }
+      }
+    }
+  }
+}