Introduce telemetry helpers in misc/api.func: _telemetry_report_exit (reports success/failure via post_tool_to_api/post_addon_to_api) and init_tool_telemetry (reads DIAGNOSTICS, starts install timer and installs an EXIT trap to auto-report). Integrate telemetry into many tools/addon and tools/pve scripts by sourcing the remote api.func and calling init_tool_telemetry (guarded with declare -f). Also apply a minor arithmetic formatting tweak in misc/build.func for RECOVERY_ATTEMPT.
