drop DOC and LIT from the pipeline (deliberately unsupported)

.IMAGE  — extensions removed from AllowedExtensions (scan gate),
bookExtensions, MimeTypes and sync/format.go maps: .doc/.lit files
are no longer scanned or indexed. classifyFormatGroup gains the
RTF and PDB reflowable arms that were missing when those rungs
shipped (rows only reclassify on creation). Scanner docs updated.

DOC + LIT have no credible JS tooling (mammoth is docx-only; LIT
needs LZX and its DRM variants are dead) and text-extraction-only
support would misrepresent what the reader can do. Verified: probe
.doc/.lit files watched but never scanned; probe .txt control
scanned; TestClassifyFormatGroup extended and passing.

Docs change granted in-session by the user (extensions + format
docs).

docs/developer/api/scanner/overview.md

@@ -32,8 +32,13 @@ The Bookhoard scanner provides comprehensive library management for ebooks, comi
 | PDF      | `.pdf`                   |
 | Kindle   | `.mobi`                  |
 | Text     | `.txt`, `.rtf`           |
-| Document | `.doc`, `.docx`          |
-| Other    | `.lit`, `.fb2`, `.pdb`   |
+| Document | `.docx`                  |
+| Other    | `.fb2`, `.pdb`           |
+
+DOC (Word 97-2003 binary) and LIT (Microsoft Reader) are deliberately
+unsupported: no credible JavaScript parser exists for either, and
+compromising on fidelity is against the project's format goals. Files
+with these extensions are not scanned.
 
 ### Comics
 

docs/developer/api/scanner/scan_library.md

@@ -18,7 +18,7 @@ Initiate a one-time scan of a library for ebooks, manga, or comics.
 
 The scanner automatically detects and processes files based on the library type:
 
-**Ebooks:** .epub, .pdf, .mobi, .txt, .rtf, .doc, .docx, .lit, .fb2, .pdb
+**Ebooks:** .epub, .pdf, .mobi, .txt, .rtf, .docx, .fb2, .pdb
 
 **Comics:** .cbz, .cbr, .cb7, .cbt, .pdf