feat(server): S3 box is for coding — OOM kills the command not the session, no tests from Claude, 4 AI sessions per member

- tool-run (CLAUDE_CODE_SHELL_PREFIX in member panes) runs each command
  Claude runs at oom_score_adj 1000 (session 300, Terminal tab 800,
  dashboard/tmux -100), so an OOM inside the capped unit kills the test
  run and tells Claude why, instead of killing the conversation.
- member-guard.js, a synchronous managed hook for ah-* accounts: denies
  test runners and container commands from Claude's Bash, and refuses
  the prompts of a session started by hand past MAX_AI_SESSIONS.
- ai-procs.js counts a member's top-level AI processes from /proc;
  spawnRun refuses a new pane past the limit (429 ESESSIONLIMIT).
Needs `agenthub server install-system` once, then a restart.

scripts/server/tool-run.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+# @file tool-run.sh
+# @description Server mode, one Linux user per account (S3): installed as
+# /opt/agenthub/libexec/tool-run and named by CLAUDE_CODE_SHELL_PREFIX in
+# every member pane (pane-launch). Claude Code runs each Bash command (and
+# hook) as `tool-run '<command string>'`. The command runs at the kernel's
+# highest OOM preference, so when memory runs out it is the command — a test
+# run, a build — that is killed, never the Claude session above it that holds
+# the conversation (pane-launch puts that one at 300). When the cgroup's OOM
+# count moved while the command ran, Claude is told why it died.
+# @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
+[ $# -gt 0 ] || exec /bin/bash
+echo 1000 >/proc/self/oom_score_adj 2>/dev/null
+cg=$(sed -n 's/^0:://p' /proc/self/cgroup 2>/dev/null)
+events=/sys/fs/cgroup${cg}/memory.events
+kills() { sed -n 's/^oom_kill //p' "$events" 2>/dev/null; }
+before=$(kills)
+/bin/bash -c "$1"
+rc=$?
+if [ "$rc" -ne 0 ] && [ -n "$before" ] && [ "$(kills)" != "$before" ]; then
+  printf '\n%s\n' "AgentHub: the server ran out of memory, so a process of this command was stopped (exit $rc). This shared server is for writing code only: do not run tests, containers or other heavy jobs here — tell the user to run them on their own machine." >&2
+fi
+exit "$rc"