feat(servers): per-server memory ceiling, because 512Mi OOMKills silently

Server pods have always had a hardcoded 512Mi limit. That is right for a
server that proxies an API and fatal for one that drives a browser: the
`docs` server (docs-mcp-server, which scrapes with headless Chromium)
idles at ~228Mi and crosses 512Mi within seconds of its first scrape.

An OOMKill is the quietest failure we have. The kernel kills it, the pod
restarts, the readiness probe passes, and the instance reads `healthy`
again — while the six scrape jobs whose queue lived in memory are gone
and the index has 17 pages in it. Nothing is logged, because the process
never got to say anything.

memoryLimitMb is declared per server, in MiB, and converted to bytes in
the container spec. NULL keeps DEFAULT_MEMORY_LIMIT, so every existing
server is bit-for-bit unchanged — a bigger default would have cost real
memory on every node for servers that do not need it.

  mcpctl create server docs --memory-limit-mb 2048 --force

Tests assert the two places a new column dies quietly: the repository's
field-by-field mapping (a column not mapped there returns "patched" and
changes nothing) and the spec built in instance.service. docs/reliability
gains the OOMKill section — the `lastState.terminated.reason` check is
what turns "it restarted again" into an answer.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JPjtnE6Gd343oRNtMU9Bcd

completions/mcpctl.bash

@@ -194,7 +194,7 @@ _mcpctl() {
       else
         case "$create_sub" in
           server)
-            COMPREPLY=($(compgen -W "-d --description --package-name --runtime --docker-image --transport --repository-url --external-url --command --container-port --replicas --env --volume --health-check-tool --health-check-args --health-check-interval --health-check-timeout --tool-call-timeout --health-check-failure-threshold --secret-delivery --entrypoint --from-template --env-from-secret --force -h --help" -- "$cur"))
+            COMPREPLY=($(compgen -W "-d --description --package-name --runtime --docker-image --transport --repository-url --external-url --command --container-port --replicas --env --volume --health-check-tool --health-check-args --health-check-interval --health-check-timeout --tool-call-timeout --memory-limit-mb --health-check-failure-threshold --secret-delivery --entrypoint --from-template --env-from-secret --force -h --help" -- "$cur"))
             ;;
           secret)
             COMPREPLY=($(compgen -W "--data --force -h --help" -- "$cur"))