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).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

.gitignore

@@ -72,4 +72,3 @@ venv/
 env/
 
 *.tar.gz
-tests/vectors/victronble_test