Add welcome message on Bluetooth Manager startup

[Copilot]

Displays a greeting when the Bluetooth Manager successfully initializes.

Changes

• Added welcome message in btrMgr_main.c after BTRMGR_Init() succeeds
• Created .gitignore to exclude autotools artifacts and build outputs

if ((lenBtrMgrResult = BTRMGR_Init()) == BTRMGR_RESULT_SUCCESS) {
    signal(SIGTERM, btrMgr_SignalHandler);
    
    printf("Hello! Welcome to Bluetooth Manager\n");
    fflush(stdout);
    
    // Continue with IARM/RBUS initialization...
}

The message appears before IARM/RBUS mode initialization, providing immediate user feedback on successful startup.

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