chore: kernel-src 归项目目录，更新路径与 gitignore

patches/ubuntu-hwe-6.17/DIFF_SUMMARY.txt

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+Default source tree (not in git): ../kernel-src/linux-hwe-6.17-6.17.0/
+
+ChromeOS v5.15 vs Ubuntu HWE 6.17 (sound/soc/intel/boards/sof_board_helpers.c)
+================================================================================
+
+Key upstream renames (not bugs by themselves):
+- dpcm_playback / dpcm_capture on DAI links -> playback_only / capture_only
+  (see include/sound/soc.h). ChromeOS set_idisp_hdmi used dpcm_playback=1;
+  6.17 uses playback_only=1 for the same iDisp HDMI BE link.
+
+Other 6.17 deltas in this file: HDA external codec widgets/routes, EXPORT_SYMBOL_NS
+string form, enum snd_soc_acpi_intel_codec renames, DMIC capture_only, etc.
+
+sof_rt5682.c differs heavily by DMI quirks and API; no Kaisa-specific string in
+either tree (board selection is via ACPI / machine driver data).
+
+Experiment patch 0002 (applies on 6.17):
+- Adds link->trigger[0/1] = SND_SOC_DPCM_TRIGGER_POST in set_idisp_hdmi_link,
+  similar to older Intel boards (e.g. bdw_rt286).
+
+Build smoke-test (object file only, not full deb):
+- make x86_64_defconfig && make prepare SKIP_STACK_VALIDATION=1
+- make sound/soc/intel/boards/sof_board_helpers.o
+
+Full Ubuntu package: fakeroot debian/rules binary-generic (needs apt build-dep
+linux-hwe-6.17, large disk/time). Install linux-image-* / linux-modules-* on Kaisa.
+
+Kaisa 真机验证（安装新 deb 并重启后）
+------------------------------------
+1. uname -r
+2. aplay -L | head -80
+3. speaker-test -D plughw:卡号,设备号 -c 2 -l 1   # 对照 HDMI 对应 PCM
+4. sudo dmesg | grep -iE 'sof|STREAM_PCM|ipc failed|pcm[0-9]' | tail -60
+5. 将输出保存到 audio_topology/collected/ 便于前后对比