Replace dead upstream images with custom build services; add retry logic

dtagdevsec/mailoney and dtagdevsec/elasticpot are unavailable on Docker Hub
("manifest unknown"), causing the entire deployment to abort and cascade-
interrupt all other image pulls.

- Convert smtp and elasticsearch to build services with custom Python
  honeypots: smtp emulates Postfix ESMTP (EHLO/AUTH/MAIL/RCPT logging),
  elasticsearch emulates ES 7.17 HTTP API (logs recon probes like /_cat/,
  /_cluster/, /_nodes/, /_security/)
- Both use ARG BASE_IMAGE so they participate in per-decky distro variation
- Add _compose_with_retry() to deployer: 3 attempts with exponential backoff
  (5s → 10s → 20s) for transient network failures; permanent errors
  ("manifest unknown", "pull access denied") are detected and not retried
- Update test_services.py and test_composer.py: smtp/elasticsearch moved
  from UPSTREAM_SERVICES to BUILD_SERVICES (314 tests passing)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

decnet/services/smtp.py

@@ -1,25 +1,28 @@
+from pathlib import Path
+
 from decnet.services.base import BaseService
 
+TEMPLATES_DIR = Path(__file__).parent.parent.parent / "templates" / "smtp"
+
 
 class SMTPService(BaseService):
     name = "smtp"
     ports = [25, 587]
-    default_image = "dtagdevsec/mailoney"
+    default_image = "build"
 
     def compose_fragment(self, decky_name: str, log_target: str | None = None) -> dict:
-        env: dict = {
-            "MAILONEY_HOSTNAME": decky_name,
-            "MAILONEY_PORTS": "25,587",
-        }
-        if log_target:
-            env["MAILONEY_LOG_TARGET"] = log_target
-        return {
-            "image": "dtagdevsec/mailoney",
+        fragment: dict = {
+            "build": {"context": str(TEMPLATES_DIR)},
             "container_name": f"{decky_name}-smtp",
             "restart": "unless-stopped",
             "cap_add": ["NET_BIND_SERVICE"],
-            "environment": env,
+            "environment": {
+                "HONEYPOT_NAME": decky_name,
+            },
         }
+        if log_target:
+            fragment["environment"]["LOG_TARGET"] = log_target
+        return fragment
 
-    def dockerfile_context(self):
-        return None
+    def dockerfile_context(self) -> Path:
+        return TEMPLATES_DIR