lekki v0.1.1 — esp-idf-sys 0.37.2 alignment

Patch over v0.1.0: lekki-mbedtls's device backend bumped esp-idf-sys
0.36 -> 0.37.2 so it shares the firmware's esp-idf-sys generation
(evorada-dongle pins sys 0.37.2 via esp-idf-svc 0.52.1). Binding
surface unchanged; device build (xtensa-esp32s3-espidf) verified green
in CI. No API or behavior change.

lekki v0.1.0 — LwM2M 1.0/1.1 client (Phase A+B+hardening)

First taggable release. Plan steps L0–L12 complete:
- Registration, DM dispatch (Read/Write/Execute/Create/Delete/Discover),
  streaming Block1, client Block2 /5 pull, TLV + text/opaque codecs.
- DTLS 1.2 PSK over mbedTLS (CID → resume → full-handshake ladder),
  no hand-written C.
- LwM2M 1.1: SenML CBOR/JSON + Read-Composite (feature lwm2m11).
- Hardening: 6 cargo-fuzz lanes, malformed-datagram robustness replay,
  docs/conformance.md; core is #![forbid(unsafe_code)].

Verified against Eclipse Leshan (live e2e). Coiote second-server
interop (T-07) still pending.