feat(cli): add interactive email import tool for EML, MBOX, and Thunderbird

- Implement `bichonctl` interactive CLI using `dialoguer`.
- Support recursive EML directory scanning with folder structure preservation.
- Support single MBOX file streaming import.
- Support Thunderbird profile import with automatic `.sbd` hierarchy detection.
- Add batch processing (Base64 encoding & batch API requests) for improved performance.

src/modules/cli/mbox/reader.rs

@@ -0,0 +1,210 @@
+use memmap2::Mmap;
+use std::fs;
+use std::io;
+use std::path::Path;
+
+pub struct MboxFile {
+    map: Mmap,
+}
+
+impl MboxFile {
+    pub fn from_file(name: &Path) -> io::Result<Self> {
+        let file = fs::File::open(name)?;
+        let metadata = file.metadata()?;
+        if metadata.len() == 0 {
+            return Err(io::Error::new(
+                io::ErrorKind::InvalidData,
+                "Empty MBOX file",
+            ));
+        }
+        let map = unsafe { Mmap::map(&file)? };
+        Ok(Self { map })
+    }
+
+    pub fn iter(&self) -> MboxReader<'_> {
+        MboxReader::new(&self.map)
+    }
+}
+
+pub struct Entry<'a> {
+    pub offset: usize,
+    pub data: &'a [u8],
+}
+
+pub struct MboxReader<'a> {
+    data: &'a [u8],
+    len: usize,
+    scan_pos: usize,
+    body_start: Option<usize>,
+}
+
+impl<'a> MboxReader<'a> {
+    fn new(data: &'a [u8]) -> Self {
+        Self {
+            data,
+            len: data.len(),
+            scan_pos: 0,
+            body_start: None,
+        }
+    }
+
+    fn is_from_line(&self, i: usize) -> bool {
+        if i + 5 > self.len {
+            return false;
+        }
+
+        if i == 0 {
+            &self.data[0..5] == b"From "
+        } else {
+            self.data[i - 1] == b'\n' && &self.data[i..i + 5] == b"From "
+        }
+    }
+
+    fn skip_from_line(&self, mut i: usize) -> usize {
+        while i < self.len && self.data[i] != b'\n' {
+            i += 1;
+        }
+        if i < self.len {
+            i += 1;
+        }
+        i
+    }
+}
+
+impl<'a> Iterator for MboxReader<'a> {
+    type Item = Entry<'a>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        while self.scan_pos < self.len {
+            if self.is_from_line(self.scan_pos) {
+                let from_pos = self.scan_pos;
+                let body_pos = self.skip_from_line(from_pos);
+
+                if let Some(start) = self.body_start {
+                    let entry = Entry {
+                        offset: start,
+                        data: &self.data[start..from_pos],
+                    };
+                    self.body_start = Some(body_pos);
+                    self.scan_pos = body_pos;
+                    return Some(entry);
+                } else {
+                    self.body_start = Some(body_pos);
+                    self.scan_pos = body_pos;
+                    continue;
+                }
+            }
+
+            self.scan_pos += 1;
+        }
+        if let Some(start) = self.body_start.take() {
+            return Some(Entry {
+                offset: start,
+                data: &self.data[start..self.len],
+            });
+        }
+        None
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use mail_parser::MessageParser;
+
+    use crate::modules::cli::mbox::gmail::determine_folder;
+
+    use super::*;
+
+    fn collect_entries(data: &[u8]) -> Vec<&[u8]> {
+        let reader = MboxReader::new(data);
+        reader.map(|e| e.data).collect()
+    }
+
+    #[test]
+    fn two_mails() {
+        let data = b"From a\nmail1\nFrom b\nmail2\n";
+        let e = collect_entries(data);
+        assert_eq!(e, vec![b"mail1\n", b"mail2\n"]);
+    }
+    #[test]
+    fn no_trailing_newline() {
+        let data = b"From a\nmail1";
+        let e = collect_entries(data);
+        assert_eq!(e, vec![b"mail1"]);
+    }
+
+    #[test]
+    fn from_inside_body() {
+        let data = b"From a\nhello\nFrom is here\nbye\n";
+        let e = collect_entries(data);
+        assert_eq!(e.len(), 2);
+    }
+
+    #[test]
+    fn inline_from_not_separator() {
+        let data = b"From a\nhello From world\n";
+        let e = collect_entries(data);
+        assert_eq!(e.len(), 1);
+    }
+
+    #[test]
+    fn realistic_mbox() {
+        let data = b"From a\nH:1\n\nbody1\nFrom b\nH:2\n\nbody2\n";
+        let e = collect_entries(data);
+        assert_eq!(e.len(), 2);
+    }
+
+    #[test]
+    fn empty_body() {
+        let data = b"From a\nFrom b\nbody\n";
+        let e = collect_entries(data);
+        assert_eq!(e[0], b"");
+        assert_eq!(e[1], b"body\n");
+    }
+
+    #[test]
+    fn only_from_line() {
+        let data = b"From a\n";
+        let e = collect_entries(data);
+        assert_eq!(e.len(), 1);
+        assert_eq!(e[0], b"");
+    }
+
+    #[test]
+    fn windows_newlines() {
+        let data = b"From a\r\nbody\r\nFrom b\r\nbody2\r\n";
+        let e = collect_entries(data);
+        assert_eq!(e.len(), 2);
+    }
+
+    #[test]
+    fn many_small_mails() {
+        let mut data = Vec::new();
+        for i in 0..1000 {
+            data.extend_from_slice(b"From a\nx\n");
+        }
+        let e = collect_entries(&data);
+        assert_eq!(e.len(), 1000);
+    }
+
+    #[test]
+    fn test11() {
+        let mbox = MboxFile::from_file(Path::new("e:\\test.mbox")).unwrap();
+
+        for e in mbox.iter() {
+            let body = e.data;
+
+            let message = MessageParser::new().parse(body).unwrap();
+            let labels = message.header("X-Gmail-Labels").unwrap().as_text().unwrap();
+            //println!("offset={} X-Gmail-Labels={:?}", e.offset, labels);
+            println!(
+                "X-Gmail-Labels={:?}, determine_folder={}",
+                labels,
+                determine_folder(labels)
+            )
+
+
+            
+        }
+    }
+}