fix(cw): add crash probes to localize adb-less flash-crash

闪回桌面且无任何 Java 日志 => 崩溃发生在 native 层 (ONNX 库内部段错误)
或进程被系统 LMK 直接杀掉 (内存不足) —— 两种情况 Java 的
uncaughtExceptionHandler 都不会触发, crash_log.txt 自然为空。

新增 CwProbe: 在关键节点向 files/probe_cw.txt 追加时间戳行:
  decoder_constructed -> load_begin -> load_session_ok / load_failed:<类名>
  -> infer_begin -> infer_done
进程若中途死亡, 最后一行的节点就是崩溃/被杀位置, 无需 adb 即可定位。

验证: :core:data:compileDebugKotlin => BUILD SUCCESSFUL

core/data/src/main/java/com/rtbishop/look4sat/core/data/cw/CwDeepDecoder.kt

@@ -87,6 +87,11 @@ class CwDeepDecoder(context: Context) : ICwDecoder {
     private val appContext = context.applicationContext
     private var loadAttempted = false
 
+    init {
+        CwProbe.init(appContext)
+        CwProbe.step("decoder_constructed")
+    }
+
     /**
      * Loads metadata and the ONNX session on first use.
      *
@@ -102,6 +107,7 @@ class CwDeepDecoder(context: Context) : ICwDecoder {
         if (session != null) return true
         if (loadAttempted) return false
         loadAttempted = true
+        CwProbe.step("load_begin")
         try {
             val metadata = JSONObject(
                 appContext.assets.open(METADATA_ASSET).bufferedReader().use { it.readText() }
@@ -122,11 +128,13 @@ class CwDeepDecoder(context: Context) : ICwDecoder {
                 setIntraOpNumThreads(threads)
             }
             session = env.createSession(modelBytes, options)
+            CwProbe.step("load_session_ok")
             Log.i(TAG, "DeepCW ready: ${modelBytes.size} bytes, ${chars.size} classes")
             return true
         } catch (t: Throwable) {
             // Catches UnsatisfiedLinkError (missing/mismatched .so) as well as
             // asset and session failures.
+            CwProbe.step("load_failed:${t.javaClass.simpleName}")
             Log.e(TAG, "DeepCW model failed to load", t)
             _errorMessage.value =
                 "CW model failed to load: ${t.message ?: t.javaClass.simpleName}"
@@ -175,6 +183,7 @@ class CwDeepDecoder(context: Context) : ICwDecoder {
     private suspend fun decodeWindow(window: FloatArray) = withContext(Dispatchers.Default) {
         val activeSession = session ?: return@withContext
         val activeEnvironment = environment ?: return@withContext
+        CwProbe.step("infer_begin frames=${window.size}")
 
         val spectrogram = CwDeepSpectrogram.compute(window)
         val frames = spectrogram.size
@@ -195,6 +204,7 @@ class CwDeepDecoder(context: Context) : ICwDecoder {
             }
         }
         _lastInferenceMs.value = (System.currentTimeMillis() - startedAt).toInt()
+        CwProbe.step("infer_done ms=${_lastInferenceMs.value}")
 
         // Replace, never append: the model rewrites earlier characters as more
         // context arrives, so appending would leave stale guesses on screen.

core/data/src/main/java/com/rtbishop/look4sat/core/data/cw/CwProbe.kt

@@ -0,0 +1,46 @@
+/*
+ * Look4Sat. Amateur radio satellite tracker and pass predictor.
+ * Copyright (C) 2019-2026 Arty Bishop and contributors.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.rtbishop.look4sat.core.data.cw
+
+import android.content.Context
+import android.util.Log
+
+/**
+ * Minimal crash-probe logger for diagnosing crashes that produce no Java
+ * stack trace (native faults, low-memory kills). Each step appends one line
+ * to `files/probe_cw.txt`; if the process dies mid-way the last line shows
+ * exactly where. No adb or logcat required.
+ */
+internal object CwProbe {
+
+    private var dir: java.io.File? = null
+
+    fun init(context: Context) {
+        dir = context.filesDir
+    }
+
+    fun step(label: String) {
+        val target = dir ?: return
+        runCatching {
+            val line = "${System.currentTimeMillis()} $label"
+            val file = java.io.File(target, "probe_cw.txt")
+            file.appendText("$line\n")
+            Log.i("CwProbe", line)
+        }
+    }
+}