v0.7.0: pure C core + Zephyr module

- Extract all decode/decrypt into a dependency-free C99 core
 (include/victronble.h, src/victronble_core.c): victronble_decode(),
 is_product_adv/key_matches pre-filters, NAN sentinels, LE accessors.
- AES-128-CTR behind a hook: weak-symbol bundled tiny-AES default,
 runtime override (victronble_set_aes_ctr) for PSA/mbedTLS/hardware.
- Arduino VictronBLE class becomes a thin wrapper over the core
 (registry + nonce dedup + rate limit); public C++ API unchanged,
 NAN converted back to the legacy 0 convention.
- Host test vectors (tests/vectors): openssl-generated ciphertext,
 independent of the bundled AES; all five payload shapes + negatives.
- Zephyr module: zephyr/module.yml + Kconfig (CONFIG_VICTRONBLE) +
 observer backend (victronble_zephyr.{h,c}) — scan cb pre-filters and
 queues, dedicated decode thread, listener callbacks, slow passive
 scan defaults, stats counters. docs/ZEPHYR_PORT.md records the plan.
- library.properties: fix URL (gitea, not the nonexistent GitHub).

tests/vectors/run.sh

@@ -0,0 +1,9 @@
+#!/bin/sh
+# Build and run the victronble core host tests (plain gcc, no framework).
+# Regenerate vectors first with: python3 gen_vectors.py
+set -e
+cd "$(dirname "$0")"
+cc -std=c99 -Wall -Wextra -Werror -I../../include -I../../src \
+    ../../src/victronble_core.c ../../src/victronble_aes_sw.c \
+    ../../src/crypto/vble_aes.c test_main.c -lm -o victronble_test
+./victronble_test