feat(config-upgrade-snapshot): live config-upgrade soak infra + fix bug-1468/bug-1469 (task 8.6)

Build the live 3-node chaotic-multi-kill config-upgrade soak scenario
(run-ha-soak.sh --config-upgrade) required by Requirements 4.1, 4.3, 6.1,
6.4. This needed genuinely new client-side infrastructure: a hand-rolled
capnp send path for OP_upgradeConfig (the auto-generated encoder is a
no-op for its Data fields, worked around the same way
xce_replconfigpush_req_raw already does), plus cmd_hostctrl/cmd_upgradeconfig
CLI commands.

Building and running this live surfaced two real production bugs, both
fixed here:

- bug-1468: an unrelated prior commit inverted OPCode_upgradeConfig's
  primary/standby dispatch guard in cluster.c, making config upgrades
  unreachable from any network client.
- bug-1469: apply_committed_entry's WAL_CONFIG_MARKER case never called
  config_activate_committed(), so the node that originates a config
  upgrade never refreshed its own in-memory state as part of committing
  it. Killing that node before some later, unrelated event happened to
  refresh it left its checkpoint permanently stale -- the first live,
  empirical reproduction of bug-857's originally hypothesized failure
  mode. Fixed by activating before the marker-triggered checkpoint write,
  since checkpoint content is built from live runtime tables that only
  reflect the reload after activation runs.

A separate, narrower checkpoint divergence (bug-1471, not config-related)
remains open and still blocks a clean soak PASS -- task 8.6 stays
in-progress until it's resolved.

src/lib/request.c

@@ -499,6 +499,94 @@ int xce_replconfigpush_req_raw(endpoint_t *ep, xce_peerinfo_t *from,
     return (enq_rc < 0) ? enq_rc : 0;
 }
 
+/*
+ * xce_upgradeconfig_req_raw: send OP_upgradeConfig with raw byte arrays.
+ *
+ * Bypasses encode_UpgradeConfigRequest (a literal no-op for the sha256/bytes
+ * Data fields — see the doc comment above upgrade_config_req_s in typemap.h;
+ * confirmed by inspection of the generated xce.build/lib/controller.capnp.c).
+ * Instead, constructs the struct Request / struct UpgradeConfigRequest
+ * directly using the capnp wire-format API (capn_new_list8 + capn_setv8),
+ * mirroring xce_replconfigpush_req_raw's exact bypass pattern.
+ *
+ * Unlike that controller-to-controller helper, this is an ordinary CLIENT
+ * request: seq and from are populated the same way the generic xce_request()
+ * populates them for every other client op (endpoint_getseq(ep), ep->peer),
+ * not passed in by the caller.
+ */
+int xce_upgradeconfig_req_raw(endpoint_t *ep,
+                              const uint8_t *sha256, size_t sha256_len,
+                              const uint8_t *bytes, size_t bytes_len)
+{
+    struct capn                 c;
+    struct capn_segment        *cs;
+    struct Request               rq;
+    struct UpgradeConfigRequest  up_req;
+    UpgradeConfigRequest_ptr     up_ptr;
+    Request_ptr                  rp;
+    io_packet_t                 *pkt;
+    int                          rc;
+
+    if (ep == NULL)
+        return -EINVAL;
+
+    if (sha256 == NULL || sha256_len == 0 || bytes == NULL || bytes_len == 0)
+        return -EINVAL;
+
+    capn_init_malloc(&c);
+    cs = capn_root(&c).seg;
+
+    memset(&rq,     0, sizeof(rq));
+    memset(&up_req, 0, sizeof(up_req));
+
+    /* sha256: write as a List(UInt8) — capn_list8 and capn_data share {capn_ptr p} */
+    {
+        capn_list8 sha_list = capn_new_list8(cs, (int)sha256_len);
+        capn_setv8(sha_list, 0, sha256, (int)sha256_len);
+        up_req.sha256.p = sha_list.p;
+    }
+
+    /* config bytes */
+    {
+        capn_list8 bytes_list = capn_new_list8(cs, (int)bytes_len);
+        capn_setv8(bytes_list, 0, bytes, (int)bytes_len);
+        up_req.bytes.p = bytes_list.p;
+    }
+
+    up_ptr = new_UpgradeConfigRequest(cs);
+    write_UpgradeConfigRequest(&up_req, up_ptr);
+
+    rq.opcode     = OPCode_upgradeConfig;
+    rq.seq        = endpoint_getseq(ep);
+    rq.body_which = Request_body_upgradeconfigrequestmsg;
+    rq.body.upgradeconfigrequestmsg = up_ptr;
+    encode_PeerInfo_ptr(cs, &rq.from, ep->peer);
+
+    rp = new_Request(cs);
+    write_Request(&rq, rp);
+    capn_setp(capn_root(&c), 0, rp.p);
+
+    pkt = (io_packet_t *)calloc(1, sizeof(*pkt));
+    if (!pkt) {
+        capn_free(&c);
+        return -ENOMEM;
+    }
+
+    pkt->sz = capn_size(&c);
+    rc = alloc_packet(pkt);
+    if (rc < 0) {
+        free(pkt);
+        capn_free(&c);
+        return -errno;
+    }
+
+    capn_write_mem(&c, (uint8_t *)pkt->data, pkt->sz, 0);
+    capn_free(&c);
+
+    int enq_rc = endpoint_enq(ep, &(pkt->link));
+    return (enq_rc < 0) ? enq_rc : 0;
+}
+
 /* wal_entry_to_wire: fill a wire WalCatchupEntry from a C entry's header
  * fields and raw payload bytes.  Sub-entry nesting is one level deep —
  * elements written here never carry their own entries list. */