Delete the DOCX text fallback: a second extractor is a second character plane

Eli: "we should not have a docx text fallback. if the main docx call doesn't
work, we need to fix that instrument, not silently fallback."

The fallback was worse than redundant. `applyTextOpsToDocx` resolves every
edit scope against `extractDocxBodyText` and nothing else, so a document that
fell through to mammoth was READ on one character plane and EDITED on
another: every offset the reader returned pointed somewhere else in the
writer. Nothing surfaced it, because falling back looks exactly like success
-- and the address grammar now being wired into the edit layer would have
inherited the same silent divergence.

Measured before removing it (rule 2): 400 documents sampled at stride 28
across the 11,293-file corpus, zero empty and zero throwing. It was carrying
nothing. A typed refusal naming the failure replaces it, so a real extraction
defect arrives as a bug report instead of as a wrong-plane edit.

Parser version bumped to 2 -- the cache is content-addressed on parser
identity, so the old fallback's output cannot be served for the new contract.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01H9ToHYJVDxfeJcJwdzrP2H