refactor(reader): extract.rs moves into ledger-reader (U0d)

D-61 (Q-9): the writer sheds the typesetter and the crate map is layered
again. The PDF/XLSX reader (extract.rs, plan P6) is now the plain library
crate ledger-reader, moved whole with git mv and no behavior change.
ledger-store depends on it instead of ledger-import, so the store no
longer builds Typst or the fonts; ledger-import re-exports it as
ledger_import::extract so gui, mcp, host and the fuzz targets compile
unchanged, and still never depends on the store. New crate carries only
the dependencies extract.rs imports (hayro, hayro-interpret, kurbo, zip,
quick-xml, thiserror); fuzz/Cargo.lock gains the new package.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HS8WZziDnyxunC23MUxrLp

crates/ledger-import/tests/extract.rs

@@ -1,7 +1,7 @@
 //! The one extractor (plan P6 step 1): a PDF's text and pages, and an
 //! XLSX's cells as exact decimal strings.
 //!
-//! Expected behavior comes from `crates/ledger-import/src/extract.rs`'s
+//! Expected behavior comes from `crates/ledger-reader/src/lib.rs`'s
 //! INVARIANTS, which come from plan/served.md P6 step 1 and D-15, D-32 and
 //! D-53.