feat: ADR-029/031 TDM sensing protocol, channel hopping, and NVS config

Implement the hardware and firmware portions of RuvSense (ADR-029) and
RuView (ADR-031) for multistatic WiFi sensing:

Rust (wifi-densepose-hardware):
- TdmSchedule: uniform slot assignments with configurable cycle period,
  guard intervals, and processing window (default 4-node 20 Hz)
- TdmCoordinator: manages sensing cycles, tracks per-slot completion,
  cumulative clock drift compensation (±10 ppm over 50 ms = 0.5 us)
- SyncBeacon: 16-byte wire format for cycle synchronization with
  drift correction offsets
- TdmSlotCompleted event for aggregator notification
- 18 unit tests + 4 doctests, all passing

Firmware (C, ESP32):
- Channel-hop table in csi_collector.c (s_hop_channels, configurable
  via csi_collector_set_hop_table)
- Timer-driven channel hopping via esp_timer at dwell intervals
- NDP frame injection stub via esp_wifi_80211_tx()
- Backward-compatible: hop_count=1 disables hopping entirely
- NVS config extension: hop_count, chan_list, dwell_ms, tdm_slot,
  tdm_node_count with bounds validation and Kconfig fallback defaults

Co-Authored-By: claude-flow <ruv@ruv.net>

firmware/esp32-csi-node/main/nvs_config.h

@@ -18,6 +18,9 @@
 #define NVS_CFG_PASS_MAX     65
 #define NVS_CFG_IP_MAX       16
 
+/** Maximum channels in the hop list (must match CSI_HOP_CHANNELS_MAX). */
+#define NVS_CFG_HOP_MAX      6
+
 /** Runtime configuration loaded from NVS or Kconfig defaults. */
 typedef struct {
     char     wifi_ssid[NVS_CFG_SSID_MAX];
@@ -25,6 +28,13 @@ typedef struct {
     char     target_ip[NVS_CFG_IP_MAX];
     uint16_t target_port;
     uint8_t  node_id;
+
+    /* ADR-029: Channel hopping and TDM configuration */
+    uint8_t  channel_hop_count;               /**< Number of channels to hop (1 = no hop). */
+    uint8_t  channel_list[NVS_CFG_HOP_MAX];   /**< Channel numbers for hopping. */
+    uint32_t dwell_ms;                        /**< Dwell time per channel in ms. */
+    uint8_t  tdm_slot_index;                  /**< This node's TDM slot index (0-based). */
+    uint8_t  tdm_node_count;                  /**< Total nodes in the TDM schedule. */
 } nvs_config_t;
 
 /**