[BUG] No audio from internal speakers on Acer Aspire AL16-31P — pin 0x14 detected and configured as speaker, but no output (Realtek + HDA) #5975

Describe the bug
No audio from the internal speakers on an Acer Aspire AL16-31P. The
Realtek codec is detected and snd_hda_codec_generic autoconfig correctly
identifies pin 0x14 as a speaker output, but no audio reaches the
internal amplifier. Headphone jack, Bluetooth and USB audio all work
correctly, so this appears to be a missing model quirk / routing issue
(EAPD or GPIO amplifier enable) rather than a hardware failure — the
speakers work fine in Windows.

What I tried to diagnose/workaround:

• Unmuted and raised all gains in alsamixer (Master, Speaker,
  Speaker Boost, Headphone)
• EAPD and GPIO manipulation via hda-verb on nodes 0x14 and 0x01
• snd_hda_intel model= probe options
• Forcing snd-intel-dspcfg dsp_driver=1 (legacy HDA) and default (SOF)
  — codec detected in both, no speaker output either way
• PipeWire restart and fresh user session

To Reproduce

1. Boot the laptop with Ubuntu (kernel 7.0.0-38-generic)
2. Play any audio through the "Built-in Audio" output
3. No sound is produced by the internal speakers; no errors are shown

Reproduction Rate
All the time (100%). It does not vary with any configuration or user
action.

Expected behavior
Internal speakers should output audio as they do in Windows on the
same hardware.

Impact
Annoyance: internal speakers are unusable; I currently rely on
Bluetooth/USB audio output as a workaround.

Environment

1. Kernel: 7.0.0-38-generic (Ubuntu distribution kernel; not built
   from source, so no commit SHA)
   SOF: not applicable to my setup — issue reproduces with legacy HDA
   driver (dsp_driver=1) as well
2. Topology: not applicable (legacy HDA path shows the same behavior)
3. Platform: Intel Alder Lake-N laptop (Acer Aspire AL16-31P),
   BIOS AL160P1_ADN_V1.15
   DMI: product_name "Aspire AL16-31P", product_sku 0000000000000000
   Codecs: Realtek Generic (address 0), Intel Generic (address 2)

Screenshots or console output
Relevant dmesg section:

Full audio dmesg log attached: dmesg-audio.txt

[ 4.684682] snd_hda_codec_generic hdaudioC0D0: autoconfig for Generic: line_outs=1 (0x14/0x0/0x0/0x0/0x0) type:speaker
[ 4.684691] snd_hda_codec_generic hdaudioC0D0: hp_outs=1 (0x15/0x0/0x0/0x0/0x0)
[ 4.684696] snd_hda_codec_generic hdaudioC0D0: Internal Mic=0x12
[ 4.693633] snd_hda_codec_generic hdaudioC0D2: autoconfig for Generic: line_outs=0 (0x0/0x0/0x0/0x0/0x0) type:line

dmesg-audio.txt