rename package doc_agent -> docfield, distribution -> docfield-extract

docs: report tuning and held-out separately, with the held-out result as headline

docs: update README

fix: shorten readme frontmatter short_description to below 60 chars

eval: correct FC-1's corpus claim, log FC-2, note cent-exact severity

docs: rename to DocField Extract, reframe as key-value extraction pipeline

docs: note specs are frozen inputs, code is authoritative

docs: update readme and add MIT license

docs: rewrite README as portfolio hero page

docs: add live Space URL to README

phase 6: curate Space requirements + fix src import (T11)

phase 6: Hugging Face Space deploy scaffolding (T11)

phase 5: set CONFIDENCE_THRESHOLD=0.50, record SROIE results (T10)

phase 0.1: project scaffold (uv, py3.11, package layout)