samples: modem: hello_hl78xx: restructure prj.conf and verbose overlay

Reorganize the sample configuration files for clarity and easier
maintenance. This introduces grouped sections with descriptive comments
and improves consistency between prj.conf and the verbose-logging
overlay.

Main updates:
* Add structured headers for system, UART, networking, modem, RAT,
  AirVantage, shell, and logging settings
* Expand verbose overlay with clearer purpose, build notes, and grouped
  modem logging options
* Improve readability by aligning comments and collecting related
  options
* No functional behavior is changed; this is a documentation and
  structure improvement

These changes make the sample configuration easier to understand and
simplify future maintenance.

Signed-off-by: Zafer SEN <zafersn93@gmail.com>

Author: zafersn

samples/drivers/modem/hello_hl78xx/overlay-swir_hl78xx-verbose-logging.conf

@@ -1,8 +1,22 @@
-# Logging
+# ============================================================================
+# Verbose Logging Configuration for HL78XX Modem
+# ============================================================================
+# Use this overlay for detailed debugging and troubleshooting
+# Build with: west build -- -DEXTRA_CONF_FILE=overlay-swir_hl78xx-verbose-logging.conf
+
+# ============================================================================
+# Logging Infrastructure
+# ============================================================================
+# Large log buffer to prevent message loss during verbose logging
 CONFIG_LOG_BUFFER_SIZE=85536
 
-# For extra verbosity
+# ============================================================================
+# Modem Debug Logging
+# ============================================================================
+# Enable debug-level logging for all modem modules
 CONFIG_MODEM_MODULES_LOG_LEVEL_DBG=y
 CONFIG_MODEM_LOG_LEVEL_DBG=y
+# Larger buffer for modem chat logs (captures AT commands and responses)
 CONFIG_MODEM_CHAT_LOG_BUFFER_SIZE=1024
+# Enable verbose debug context for HL78XX driver
 CONFIG_MODEM_HL78XX_LOG_CONTEXT_VERBOSE_DEBUG=y

samples/drivers/modem/hello_hl78xx/prj.conf

@@ -5,67 +5,72 @@
 
 # The HL78xx driver gets its IP settings from the cell network
 
-#system
+# ============================================================================
+# System Configuration
+# ============================================================================
 CONFIG_HEAP_MEM_POOL_SIZE=4096
 CONFIG_MAIN_STACK_SIZE=4096
 CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=4096
 CONFIG_POSIX_API=y
 
-#PM
+# ============================================================================
+# Power Management (Optional)
+# ============================================================================
 # CONFIG_PM_DEVICE=y
 
-#uart
+# ============================================================================
+# UART Configuration
+# ============================================================================
 CONFIG_UART_ASYNC_API=y
+# CONFIG_UART_INTERRUPT_DRIVEN=y
+# CONFIG_MODEM_BACKEND_UART_ASYNC_HWFC=y
 
-# Generic networking options
+# ============================================================================
+# Networking Stack
+# ============================================================================
 CONFIG_NETWORKING=y
 CONFIG_NET_UDP=y
 CONFIG_NET_TCP=y
 CONFIG_NET_IPV6=n
 CONFIG_NET_IPV4=y
 CONFIG_NET_SOCKETS=y
-
 # DNS
 CONFIG_DNS_RESOLVER=y
 CONFIG_NET_SOCKETS_DNS_TIMEOUT=12000
-
 # Wait for the network to be ready
 CONFIG_NET_SAMPLE_COMMON_WAIT_DNS_SERVER_ADDITION=y
-
 # Network management
 CONFIG_NET_MGMT=y
 CONFIG_NET_MGMT_EVENT=y
 # NB-IoT has large latency, so increase timeouts. It is ok to use this for Cat-M1 as well.
 CONFIG_NET_SOCKETS_CONNECT_TIMEOUT=15000
 CONFIG_NET_CONNECTION_MANAGER=y
-
 # Network buffers
 CONFIG_NET_PKT_RX_COUNT=32
 CONFIG_NET_PKT_TX_COUNT=16
 CONFIG_NET_BUF_RX_COUNT=64
 CONFIG_NET_BUF_TX_COUNT=32
 
-# Modem driver
+# ============================================================================
+# Modem Driver - HL78XX
+# ============================================================================
 CONFIG_MODEM=y
-
 #hl78xx modem
 CONFIG_MODEM_HL78XX=y
-
 # Statistics
 CONFIG_MODEM_STATS=y
 
-# shell
-CONFIG_SHELL=y
-CONFIG_MODEM_HL78XX_AT_SHELL=y
-CONFIG_MODEM_AT_SHELL_COMMAND_MAX_SIZE=256
-
-#apn source
+# ============================================================================
+# APN Configuration (Disabled - using defaults)
+# ============================================================================
 # CONFIG_MODEM_HL78XX_APN_SOURCE_KCONFIG=y
 # CONFIG_MODEM_HL78XX_APN="internet"
 # CONFIG_MODEM_HL78XX_APN_SOURCE_ICCID=y
 # CONFIG_MODEM_HL78XX_APN_PROFILES="hologram=23450, wm=20601, vodafone=8988239, em=8988303"
 
-# RAT selection
+# ============================================================================
+# Radio Access Technology (RAT) Configuration
+# ============================================================================
 CONFIG_MODEM_HL78XX_AUTORAT=n
 # CONFIG_MODEM_HL78XX_AUTORAT_PRL_PROFILES="2,1,3"
 # CONFIG_MODEM_HL78XX_AUTORAT_NB_BAND_CFG="3,8,20,28"
@@ -75,13 +80,28 @@ CONFIG_MODEM_HL78XX_AUTORAT=n
 # Stay in boot mode until registered to a network
 # CONFIG_MODEM_HL78XX_STAY_IN_BOOT_MODE_FOR_ROAMING=y
 
-# Enable AirVantage support
+# ============================================================================
+# AirVantage Over-The-Air (OTA) Support
+# ============================================================================
 CONFIG_MODEM_HL78XX_AIRVANTAGE=y
 CONFIG_MODEM_HL78XX_AIRVANTAGE_USER_AGREEMENT=y
 CONFIG_MODEM_HL78XX_AIRVANTAGE_UA_CONNECT_AIRVANTAGE=y
 CONFIG_MODEM_HL78XX_AIRVANTAGE_UA_DOWNLOAD_FIRMWARE=y
 CONFIG_MODEM_HL78XX_AIRVANTAGE_UA_INSTALL_FIRMWARE=y
-#  Monitor modem events
+
+# ============================================================================
+# Shell and Debug Tools
+# ============================================================================
+CONFIG_SHELL=y
+CONFIG_MODEM_HL78XX_AT_SHELL=y
+CONFIG_MODEM_AT_SHELL_COMMAND_MAX_SIZE=256
+
+# ============================================================================
+# Event Monitoring
+# ============================================================================
 CONFIG_HL78XX_EVT_MONITOR=y
+
+# ============================================================================
 # Logging
+# ============================================================================
 CONFIG_LOG=y