v0.2.0

Fixed

• INMP441 I²S aliasing when bits_per_sample: 16bit is set
  (#7).
  Setting bits_per_sample: 16bit on the microphone: block causes
  the I²S peripheral to misalign the 24-bit INMP441 data word, halving
  the effective sample rate and aliasing all energy above 8 kHz back
  onto the lower half of the spectrum. The fix is to use
  bits_per_sample: 32bit — the 32-bit frame keeps the word correctly
  aligned; the 8 LSBs are padding zeros and the driver handles them
  correctly.

Added

• DC blocker. A dedicated 1-pole high-pass at a fixed 5 Hz now
  sits upstream of every other DSP stage and runs by default on every
  packet — its only job is to kill the DC offset MEMS capsules
  (INMP441 and friends) ship with, before it eats headroom in any of
  the downstream stages. Separates concerns cleanly: the DC
  blocker is hygiene; the user-tunable low-cut is tone shaping. One
  MAC per sample, sub-audible cutoff. Note: the default install
  is no longer bit-identical to v0.1 — the DC blocker runs by
  default. The audible change is the removal of MEMS DC bias, which
  is desirable on every device the component targets.
• Low-cut bypass at 0 Hz. The low-cut slider now ranges from
  0 Hz to 500 Hz, with anything below the existing active
  minimum (20 Hz) disabling the stage entirely — mirroring how
  16 kHz (Nyquist) already disables the high-cut. Dragging the
  slider to 0 is the natural "off" position. The always-on DC
  blocker keeps running in either case, so disabling the audible
  low-cut never re-introduces DC bias downstream.

Changed

• Cut filters upgraded to 2nd-order Butterworth. Both the low-cut
  and high-cut stages now use a 2nd-order Butterworth (biquad) shape
  instead of the previous 1-pole IIR, doubling the rolloff from
  −6 dB/oct to −12 dB/oct. At the default 100 Hz low-cut, 50 Hz
  rumble is now ~12 dB rejected (vs ~6 dB), so HVAC and handling noise
  drop noticeably more without moving the cutoff up into the voice
  band. The Butterworth's defining feature — a maximally-flat
  passband — also means voice timbre is preserved cleanly instead
  of being gently tilted by the 1-pole's roll-in starting an octave
  above the cutoff. The −3 dB cutoff frequency convention is unchanged,
  so any persisted Home Assistant slider value keeps the same audible
  meaning; the slope at the cutoff is the only thing that changes.
  Implementation uses single-precision float in a direct-form-I
  biquad — the same audio cost lands on every supported MCU
  (ESP32-S3 uses its FPU, S2 and C3 use software float) rather than
  depending on FPU-only fixed-point math that would have to choose one
  target. User-facing config (cutoff ranges, defaults,
  bypass-at-Nyquist behaviour) is unchanged. See
  docs/images/filter-response.png
  for a side-by-side magnitude plot, regenerable via
  scripts/plot_filter_response.py.