feat(settings): admin switch to allow or block members' test runs

Settings → AI tools → Tests on this server (admin, S3 only). Stored in
/opt/agenthub/app/member-policy.json, which member-guard.js reads as the
member at each Bash call — no restart; no file = blocked. GET/PUT
/api/ai-tools/member-policy, audited, 409 ENOS3 outside S3.

scripts/member-guard.js

@@ -8,7 +8,8 @@
  *
  *  - `PreToolUse` (matcher Bash): denies a test run or a container command
  *    (`isHeavy`) — the member commits, pulls the branch on their own machine
- *    and runs it there. Claude gets the reason and stops trying.
+ *    and runs it there. Claude gets the reason and stops trying. An admin
+ *    can allow them again (Settings → AI tools, server/lib/member-policy.js).
  *  - `UserPromptSubmit`: a member runs at most `MAX_AI_SESSIONS` AI sessions
  *    at once (server/lib/ai-procs.js). The dashboard refuses a pane past the
  *    limit itself (ESESSIONLIMIT); this catches a `claude` typed into a
@@ -25,6 +26,7 @@ const os = require("node:os");
 const path = require("node:path");
 
 const procs = require(path.join(__dirname, "..", "server", "lib", "ai-procs.js"));
+const policy = require(path.join(__dirname, "..", "server", "lib", "member-policy.js"));
 
 /** Test runners and container tools, by the program a command segment runs. */
 const HEAVY_BINS = new Set([
@@ -139,8 +141,12 @@ const DENY_REASON =
   "run them. Finish the change, tell the user which tests to run, and let them " +
   "commit, pull the branch on their own machine and test there.";
 
-function guardTool(input) {
-  if (input.tool_name !== "Bash" || !isHeavy(input.tool_input?.command)) return;
+/** The admin's switch (Settings → AI tools), beside this script in the app root. */
+const testsAllowed = () =>
+  policy.read(path.join(__dirname, "..", policy.FILE)).allowTests === true;
+
+function guardTool(input, allowed = testsAllowed()) {
+  if (allowed || input.tool_name !== "Bash" || !isHeavy(input.tool_input?.command)) return;
   process.stdout.write(
     JSON.stringify({
       hookSpecificOutput: {