Add load test harness for pool and fleet sizing

Adds the scripts used to size the connection pool and validate fleet polling under load: burst arrival and mixed workload drivers, pool and resource samplers, a UI probe, host seed/drop SQL, and a gevent Dockerfile. Hosts are addressed by compose service name (api:5001) rather than a local path, so the harness runs against any stack rather than one machine.

loadtest_token.py mints a scoped collector token named LOADTEST and prints the secret once, then revokes only that token by name so a real collector token is never touched. envkeyfallback is false, so the harness needs a genuine managed token rather than an env key.

scripts/loadtest/loadtest_token.py

@@ -0,0 +1,62 @@
+"""Mint a temporary collector token for the load test, or revoke it after.
+
+WHY a minted token: plugin.endpoints.envkeyfallback is false, which is the
+agent kill switch working as intended - the env key no longer authorizes. The
+harness therefore needs a real managed token scoped collector.ingest.endpoints,
+exactly like a live agent.
+
+The token is named LOADTEST so revoke() removes only this one and never touches
+the real agent keys.
+
+Usage (inside the api container, with PYTHONPATH=/app and cwd /app):
+    python loadtest_token.py mint    # prints the secret once
+    python loadtest_token.py revoke
+"""
+import sys
+
+from shopdb import create_app, db
+from shopdb.core.models.apitoken import ApiToken
+
+TOKEN_NAME = 'LOADTEST temporary collector token'
+SCOPE = 'collector.ingest.endpoints'
+
+
+def mint():
+    existing = ApiToken.query.filter_by(name=TOKEN_NAME).first()
+    if existing is not None:
+        db.session.delete(existing)
+        db.session.commit()
+    owner = ApiToken.query.filter(
+        ApiToken.scopes.like('%' + SCOPE + '%')).first()
+    if owner is None:
+        raise SystemExit('no existing collector token to copy ownership from')
+    secret = ApiToken.generate_secret()
+    token = ApiToken(
+        userid=owner.userid,
+        name=TOKEN_NAME,
+        tokenprefix=ApiToken.prefix_of(secret),
+        tokenhash=ApiToken.hash_secret(secret),
+    )
+    token.scopelist = [SCOPE]
+    db.session.add(token)
+    db.session.commit()
+    print(secret)
+
+
+def revoke():
+    removed = ApiToken.query.filter_by(name=TOKEN_NAME).delete()
+    db.session.commit()
+    print('revoked %d loadtest token(s)' % removed)
+
+
+if __name__ == '__main__':
+    action = sys.argv[1] if len(sys.argv) > 1 else ''
+    app = create_app()
+    with app.app_context():
+        if action == 'mint':
+            mint()
+        elif action == 'revoke':
+            revoke()
+        else:
+            print(__doc__)
+            sys.exit(2)