prain stack: requires_NAME refuses to start without its services, merged --help

scripts/prain.conf.example

@@ -7,8 +7,9 @@ PRAIN_ROOT=/home/fabian/coding/misc/prain
 PRAIN_SERVICES="vllm web"          # `prain up` starts in this order, `prain down` stops in reverse
 
 # cmd_NAME: what service prain.NAME runs. ready_NAME: URL that answers once it can serve
-# (`prain up` waits for it, PRAIN_READY_TIMEOUT seconds, default 900). need_NAME: services
-# it depends on (OpenRC starts them first and stops it with them).
+# (`prain up` waits for it, PRAIN_READY_TIMEOUT seconds, default 900). requires_NAME:
+# services that must already be up (their ready URL answers); if not, NAME refuses to start
+# and says so. They are never started for it.
 cmd_vllm='prain serve build/agent-int4.toml models/gemma-4-26B-A4B-it-Uncensored-MAX --
   --served-model-name gemma4 --language-model-only --max-model-len 16384
   --max-num-batched-tokens 1024 --enable-prefix-caching --port 8000
@@ -16,4 +17,4 @@ cmd_vllm='prain serve build/agent-int4.toml models/gemma-4-26B-A4B-it-Uncensored
 ready_vllm=http://127.0.0.1:8000/health
 
 cmd_web='prain web --host 0.0.0.0 --port 8080 --url http://127.0.0.1:8000 --config build/agent-int4.toml'
-need_web=vllm
+requires_web=vllm