Add configurable max hops filter for auto-add contacts

Filter auto-add of new contacts by hop count (issues #1533, #1546).
Setting is configurable from the companion app via extended
CMD_SET/GET_AUTOADD_CONFIG protocol (0 = no limit, 1-63 = max hops).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/helpers/BaseChatMesh.h

@@ -98,6 +98,7 @@ protected:
   virtual bool shouldAutoAddContactType(uint8_t type) const { return true; }
   virtual void onContactsFull() {};
   virtual bool shouldOverwriteWhenFull() const { return false; }
+  virtual uint8_t getAutoAddMaxHops() const { return 0; }  // 0 = no limit, 1-63 = max hops for auto-add
   virtual void onContactOverwrite(const uint8_t* pub_key) {};
   virtual void onDiscoveredContact(ContactInfo& contact, bool is_new, uint8_t path_len, const uint8_t* path) = 0;
   virtual ContactInfo* processAck(const uint8_t *data) = 0;