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

AGENTS.md

@@ -160,7 +160,7 @@ clone, with status. Rules:
   `company.timezone`: "today" is computed by the caller and passed in;
   the core still reads no clock). New dependencies need justification in
   the commit message. No I/O, no networking, no time-source in the core.
-- Future crates (`ledger-store`, `ledger-import`, `ledger-oracle`, `books-app`)
+- Future crates (`ledger-store`, `ledger-import`, `ledger-reader`, `ledger-oracle`, `books-app`)
   depend inward toward the core, never the reverse. See `docs/architecture.md`.
 
 ## Working here