docs(readme): tighten ESP32-C6 row to match empirical witness (ADR-110)

Original row said C6 *has* HE-LTF tagging + multi-node sync + 5µA
hibernation as if they were active features. Reality per
WITNESS-LOG-110:

- Wire format VERIFIED (17 unit tests across firmware/Rust/Python)
- ESP-NOW transport VERIFIED on 1 board (1151 tx, 0 fail in 120s soak)
- TWT graceful NACK VERIFIED live (AP isn't 11ax → INVALID_ARG handled)
- HE-LTF live capture: BLOCKED on 11ax AP availability
- 5µA hibernation: datasheet number, not a measurement (no INA)
- 802.15.4 RX: known broken in IDF v5.4, ESP-NOW is the workaround

New row leads with 'wire format ready' + 'hardware-gated' to set
honest expectations, and links to docs/WITNESS-LOG-110.md so readers
can see the full empirical/claimed split themselves.

Ref: ruvnet/RuView#762, draft PR #764

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

README.md

@@ -114,7 +114,7 @@ node scripts/mincut-person-counter.js --port 5006  # Correct person counting
 > |--------|----------|------|----------|-------------|
 > | **ESP32 + Cognitum Seed** (recommended) | ESP32-S3 + [Cognitum Seed](https://cognitum.one) | ~$140 | Yes | Presence, motion, breathing, heart rate, fall detection, multi-person counting, 17-keypoint pose (signed Cog binary), 105-cog catalog, persistent vector store, kNN search, witness chain, MCP proxy |
 > | **ESP32 Mesh** | 3-6× ESP32-S3 + WiFi router | ~$54 | Yes | Same capabilities as above without the persistent-memory features |
-> | **ESP32-C6 research node** ([ADR-110](docs/adr/ADR-110-esp32-c6-firmware-extension.md)) | ESP32-C6-DevKit ($6–10) | ~$10 | Yes (Wi-Fi 6) | Same CSI pipeline as S3 **plus** HE-LTF subcarrier tagging (242 / HE20), 802.15.4 mesh time-sync for multi-node clock alignment without WiFi airtime, TWT-bounded deterministic CSI cadence, ~5 µA LP-core hibernation for battery seed nodes |
+> | **ESP32-C6 research node** ([ADR-110](docs/adr/ADR-110-esp32-c6-firmware-extension.md), [witness](docs/WITNESS-LOG-110.md)) | ESP32-C6-DevKit ($6–10) | ~$10 | Yes (Wi-Fi 6 capable) | Same CSI pipeline as S3 with the dual-target firmware. **Wire format ready** for HE-LTF PPDU tagging in ADR-018 bytes 18-19 (firmware encoder + Rust + Python decoders verified end-to-end in 17 unit tests), ESP-NOW cross-node sync (1151 tx 0 fail soak), and TWT graceful-NACK fallback (live exercised). **Hardware-gated**: HE-LTF live subcarrier capture needs an 11ax AP; ~5 µA LP-core hibernation needs an INA meter to measure; 802.15.4 RX is broken in IDF v5.4 (workaround: ESP-NOW transport for cross-node sync). See witness log for the empirical / claimed split. |
 > | **Research NIC** | Intel 5300 / Atheros AR9580 | ~$50-100 | Yes | Full CSI with 3x3 MIMO |
 > | **Any WiFi** | Windows, macOS, or Linux laptop | $0 | No | RSSI-only: coarse presence and motion (see [tutorial #36](https://github.com/ruvnet/RuView/issues/36)) |
 >