docs(arje): organiza core/ + seeds canónicas + boot reproducible

- crates/core/README.md: agrupamiento lógico de los 31 crates absorbidos
  de arje (ente-*) y del protocolo brahman (brahman-*) en 6 grupos —
  Init/PID 1, contratos, discovery, IPC+CAS, cerebro, 14 shims compat
  systemd. No se movieron crates físicamente (rompería paths
  cross-workspace).

- seeds/arje-minimal.card.json: PID1 + /bin/sh, smoke test QEMU.
- seeds/arje-prod.card.json: PID1 + 14 shims compat + tmpfiles/binfmt
  one-shots + echo + getty (16 children). Validados con
  brahman_card::Card::validate.
- seeds/validate.sh: carga la seed vía ente-zero en dev mode.

- scripts/build-arje-initrd.sh: empaqueta CPIO+gzip newc layout
  /init→/sbin/ente-zero, /usr/sbin/ente-*-compat, /ente/seed.card.json,
  /bin/{sh,...} (busybox o glibc+ldd). Tested: produce 20 MB initrd OK.
- scripts/run-arje-qemu.sh: qemu-system-x86_64 con KVM auto-detect,
  -kernel/-initrd/-append "rdinit=/init console=ttyS0,115200 panic=10".

- docs/arje-boot.md: doc end-to-end — layout initramfs, QEMU (con kernel
  del host o externo), GRUB bare metal, Proxmox/libvirt args:, schema
  de Card con todas las validaciones, debugging (sockets de
  introspección, snapshot/restore, metrics), checklist pre-deploy.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

seeds/arje-minimal.card.json

@@ -0,0 +1,62 @@
+{
+  "schema_version": 1,
+  "id": "01J8YVKZP0M0M0M0M0M0M0M0M1",
+  "lineage": null,
+  "label": "arje.seed.minimal",
+  "provides": ["Spawn", "Journal"],
+  "requires": [],
+  "permissions": {
+    "networking": "none",
+    "filesystem": "read-write",
+    "ipc": { "allow": [] },
+    "processes": true
+  },
+  "soma": {
+    "namespaces": {
+      "mount": false, "pid": false, "net": false,
+      "uts": false, "ipc": false, "user": false, "cgroup": false
+    },
+    "rlimits": { "mem_bytes": null, "nproc": null, "nofile": null },
+    "cgroup": { "path": "ente.slice/zero", "cpu_weight": null, "io_weight": null },
+    "cpu_affinity": null
+  },
+  "payload": "Virtual",
+  "supervision": "OneShot",
+  "lifecycle": "daemon",
+  "priority": "critical",
+  "flow": { "input": [], "output": [] },
+  "genesis": [
+    {
+      "schema_version": 1,
+      "id": "01J8YVKZP0M0M0M0M0M0M0M0M2",
+      "lineage": null,
+      "label": "shell",
+      "provides": [],
+      "requires": [],
+      "permissions": {
+        "networking": "none",
+        "filesystem": "read-write",
+        "ipc": { "allow": [] },
+        "processes": true
+      },
+      "soma": {
+        "namespaces": { "mount": false, "pid": false, "net": false, "uts": false, "ipc": false, "user": false, "cgroup": false },
+        "rlimits": { "mem_bytes": null, "nproc": null, "nofile": null },
+        "cgroup": { "path": "ente.slice/shell", "cpu_weight": null, "io_weight": null },
+        "cpu_affinity": null
+      },
+      "payload": {
+        "Native": {
+          "exec": "/bin/sh",
+          "argv": ["-i"],
+          "envp": [["PATH", "/bin:/usr/bin"], ["TERM", "linux"], ["PS1", "arje# "]]
+        }
+      },
+      "supervision": { "Restart": { "initial": 100, "max": 30000 } },
+      "lifecycle": "daemon",
+      "priority": "high",
+      "flow": { "input": [], "output": [] },
+      "genesis": []
+    }
+  ]
+}