op/doma/testnet: add Celestia Alt-DA support (celestiaorg/op-alt-da:v0.15.0)

- Add relay template (templates/relays/celestia.doma.yml) for op-alt-da
- Add celestia relay config to op/doma stack in context.yml
- Add relay: celestia to op/doma testnet in config.yml
- Add op-node.doma.yml template with ALTDA env vars gated on relay_name
- Update op/doma/testnet/rollup.json with complete config including alt_da block

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

op/reth/doma-testnet-op-reth-pruned-trace.yml

@@ -145,6 +145,9 @@ services:
       - 18893:18893
       - 18893:18893/udp
     environment:
+      - OP_NODE_ALTDA_DA_SERVER=http://doma-testnet-op-reth-pruned-relay:3100
+      - OP_NODE_ALTDA_DA_SERVICE=true
+      - OP_NODE_ALTDA_ENABLED=true
       - OP_NODE_L1_BEACON=${ETHEREUM_SEPOLIA_BEACON_REST}
       - OP_NODE_L1_BEACON_ARCHIVER=${ETHEREUM_SEPOLIA_BEACON_ARCHIVER}
       - OP_NODE_L1_ETH_RPC=${DOMA_TESTNET_L1_EXECUTION_RPC:-${ETHEREUM_SEPOLIA_EXECUTION_RPC}}
@@ -183,6 +186,8 @@ services:
         condition: service_completed_successfully
       doma-testnet-op-reth-pruned:
         condition: service_started
+      doma-testnet-op-reth-pruned-relay:
+        condition: service_started
     networks:
       - chains
     volumes:
@@ -202,6 +207,25 @@ services:
       - ${NO_SSL:+traefik.http.routers.doma-testnet-op-reth-pruned-trace-node.rule=PathPrefix(`/doma-testnet-op-reth-pruned/node`)}
       - traefik.http.routers.doma-testnet-op-reth-pruned-trace-node.middlewares=doma-testnet-op-reth-pruned-trace-node-stripprefix, ipallowlist
 
+  doma-testnet-op-reth-pruned-relay:
+    image: ${DOMA_CELESTIA_IMAGE:-ghcr.io/celestiaorg/op-alt-da}:${DOMA_TESTNET_CELESTIA_VERSION:-v0.15.0}
+    expose:
+      - 3100
+    environment:
+      - OP_ALTDA_ADDR=0.0.0.0
+      - OP_ALTDA_CELESTIA_AUTH_TOKEN=
+      - OP_ALTDA_CELESTIA_NAMESPACE=0000000000000000000000000000000000000000000442a8f0ad97d133
+      - OP_ALTDA_CELESTIA_SERVER=${CELESTIA_MOCHA_RPC}
+      - OP_ALTDA_PORT=3100
+    restart: unless-stopped
+    networks:
+      - chains
+    volumes:
+      - ./op/doma/testnet:/config
+    logging: *logging-defaults
+    labels:
+      - prometheus-scrape.enabled=false
+
 volumes:
   doma-testnet-op-reth-pruned-trace: