agent: lumotia-rebrand — drop MagnotiaError prefix, now lumotia_core::Error

Phase 3 of the rebrand cascade per locked decision D4. MagnotiaError ->
Error in crates/core/src/error.rs (the crate name already qualifies it).
92 usages across 14 .rs files renamed via word-boundary sed.

One collision required disambiguation: lumotia_storage already had its
own local Error type (introduced by the slop-pass Area A residuals work).
crates/storage/src/error.rs aliases the imported core error as CoreError
on import; the From<Error> for CoreError boundary impl and the
CoreError::Storage construction site use the alias.

cargo build --workspace passes. cargo test --workspace: 330 pass, 0 fail.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/audio/src/streaming_resample.rs

@@ -28,7 +28,7 @@ use rubato::{
 };
 
 use lumotia_core::constants::WHISPER_SAMPLE_RATE;
-use lumotia_core::error::{MagnotiaError, Result};
+use lumotia_core::error::{Error, Result};
 
 /// Number of input samples the rubato resampler consumes per `process()`
 /// call. Matches the chunk size used in `resample::resample_to_16khz`.
@@ -51,7 +51,7 @@ impl StreamingResampler {
     /// rubato rejects the requested ratio.
     pub fn new(from_rate: u32) -> Result<Self> {
         if from_rate == 0 {
-            return Err(MagnotiaError::AudioDecodeFailed(
+            return Err(Error::AudioDecodeFailed(
                 "StreamingResampler: input sample rate is 0".into(),
             ));
         }
@@ -78,7 +78,7 @@ impl StreamingResampler {
             1, // mono
         )
         .map_err(|e| {
-            MagnotiaError::AudioDecodeFailed(format!("StreamingResampler init failed: {e}"))
+            Error::AudioDecodeFailed(format!("StreamingResampler init failed: {e}"))
         })?;
 
         Ok(Self::Sinc {
@@ -110,7 +110,7 @@ impl StreamingResampler {
                     let chunk: Vec<f32> = residual.drain(..INPUT_CHUNK).collect();
                     let input = vec![chunk];
                     let result = resampler.process(&input, None).map_err(|e| {
-                        MagnotiaError::AudioDecodeFailed(format!(
+                        Error::AudioDecodeFailed(format!(
                             "StreamingResampler process failed: {e}"
                         ))
                     })?;
@@ -144,7 +144,7 @@ impl StreamingResampler {
 
                 let input = vec![chunk];
                 let result = resampler.process(&input, None).map_err(|e| {
-                    MagnotiaError::AudioDecodeFailed(format!(
+                    Error::AudioDecodeFailed(format!(
                         "StreamingResampler flush failed: {e}"
                     ))
                 })?;