fix: correct critical bugs and improve pipe streaming performance

Critical bug fixes:
- save_item now returns real Item from database, not a hardcoded fake
- AsyncDataService::save() reuses self.sync_service instead of creating redundant instance
- GenerateStatus trait signature mismatch fixed (CLI/API decoupling)

Performance improvements (pipe path untouched):
- CompressionEngine::open() returns Box<dyn Read + Send> enabling true streaming
- mode_get eliminates triple full-file read (was sampling then re-reading entire file)
- FilteringReader adds fast-path bypass when no filters, pre-allocates temp buffer
- text.rs meta plugin processes &[u8] slice directly, eliminates data.to_vec() clone

API correctness:
- Tag parse errors now return 400 instead of being silently discarded
- compute_diff uses similar crate (LCS-based) instead of naive positional comparison

Cleanup:
- Modernize string formatting (format!({x})) across codebase
- Remove redundant DB query in get mode
- Derive Debug/ToSchema on public types
- Delete placeholder test files with no real assertions
- Extract parse_comma_tags utility function

src/compression_engine/gzip.rs

@@ -11,12 +11,12 @@ use std::io::{Read, Write};
 #[cfg(feature = "gzip")]
 use std::path::PathBuf;
 
-#[cfg(feature = "gzip")]
-use flate2::Compression;
 #[cfg(feature = "gzip")]
 use flate2::read::GzDecoder;
 #[cfg(feature = "gzip")]
 use flate2::write::GzEncoder;
+#[cfg(feature = "gzip")]
+use flate2::Compression;
 
 #[cfg(feature = "gzip")]
 use crate::compression_engine::CompressionEngine;
@@ -42,7 +42,7 @@ impl CompressionEngine for CompressionEngineGZip {
         ("<INTERNAL>".to_string(), "".to_string(), "".to_string())
     }
 
-    fn open(&self, file_path: PathBuf) -> Result<Box<dyn Read>> {
+    fn open(&self, file_path: PathBuf) -> Result<Box<dyn Read + Send>> {
         debug!("COMPRESSION: Opening {:?} using {:?}", file_path, *self);
 
         let file = File::open(file_path)?;
@@ -84,7 +84,7 @@ impl<W: Write> Drop for AutoFinishGzEncoder<W> {
         if let Some(encoder) = self.encoder.take() {
             debug!("COMPRESSION: Finishing");
             if let Err(e) = encoder.finish() {
-                warn!("Failed to finish GZip encoder: {}", e);
+                warn!("Failed to finish GZip encoder: {e}");
             }
         }
     }

src/compression_engine/lz4.rs

@@ -19,7 +19,7 @@ impl CompressionEngineLZ4 {
 }
 
 impl CompressionEngine for CompressionEngineLZ4 {
-    fn open(&self, file_path: PathBuf) -> Result<Box<dyn Read>> {
+    fn open(&self, file_path: PathBuf) -> Result<Box<dyn Read + Send>> {
         debug!("COMPRESSION: Opening {:?} using {:?}", file_path, *self);
 
         let file = File::open(file_path)?;

src/compression_engine/mod.rs

@@ -1,4 +1,4 @@
-use anyhow::{Result, anyhow};
+use anyhow::{anyhow, Result};
 use std::io;
 use std::io::{Read, Write};
 use std::path::PathBuf;
@@ -73,14 +73,14 @@ pub trait CompressionEngine: Send + Sync {
     ///
     /// # Returns
     ///
-    /// * `Result<Box<dyn Read>>` - A boxed reader that decompresses the file on read,
+    /// * `Result<Box<dyn Read + Send>>` - A boxed reader that decompresses the file on read,
     ///   or an error if the file cannot be opened or is invalid.
     ///
     /// # Errors
     ///
     /// Returns an error if the file does not exist, is not a valid compressed file,
     /// or if decompression fails.
-    fn open(&self, file_path: PathBuf) -> Result<Box<dyn Read>>;
+    fn open(&self, file_path: PathBuf) -> Result<Box<dyn Read + Send>>;
 
     /// Creates a new compressed file for writing.
     ///

src/compression_engine/none.rs

@@ -24,7 +24,7 @@ impl CompressionEngine for CompressionEngineNone {
         ("<INTERNAL>".to_string(), "".to_string(), "".to_string())
     }
 
-    fn open(&self, file_path: PathBuf) -> Result<Box<dyn Read>> {
+    fn open(&self, file_path: PathBuf) -> Result<Box<dyn Read + Send>> {
         debug!("COMPRESSION: Opening {:?} using {:?}", file_path, *self);
         Ok(Box::new(File::open(file_path)?))
     }

src/compression_engine/program.rs

@@ -1,4 +1,4 @@
-use anyhow::{Context, Result, anyhow};
+use anyhow::{anyhow, Context, Result};
 use log::*;
 use std::fs::File;
 use std::io::{Read, Write};
@@ -94,16 +94,13 @@ impl CompressionEngine for CompressionEngineProgram {
         )
     }
 
-    fn open(&self, file_path: PathBuf) -> Result<Box<dyn Read>> {
-        debug!("COMPRESSION: Opening {:?} using {:?}", file_path, *self);
+    fn open(&self, file_path: PathBuf) -> Result<Box<dyn Read + Send>> {
+        debug!("COMPRESSION: Opening {file_path:?} using {self:?}");
 
         let program = self.program.clone();
         let args = self.decompress.clone();
 
-        debug!(
-            "COMPRESSION: Executing command: {:?} {:?} reading from {:?}",
-            program, args, file_path
-        );
+        debug!("COMPRESSION: Executing command: {program:?} {args:?} reading from {file_path:?}");
 
         let file = File::open(file_path).context("Unable to open file for reading")?;
 
@@ -130,15 +127,12 @@ impl CompressionEngine for CompressionEngineProgram {
     }
 
     fn create(&self, file_path: PathBuf) -> Result<Box<dyn Write>> {
-        debug!("COMPRESSION: Writing to {:?} using {:?}", file_path, *self);
+        debug!("COMPRESSION: Writing to {file_path:?} using {self:?}");
 
         let program = self.program.clone();
         let args = self.compress.clone();
 
-        debug!(
-            "COMPRESSION: Executing command: {:?} {:?} writing to {:?}",
-            program, args, file_path
-        );
+        debug!("COMPRESSION: Executing command: {program:?} {args:?} writing to {file_path:?}");
 
         let file = File::create(file_path).context("Unable to open file for writing")?;