release: 1.0.0 -- the exported Python surface is frozen under semver

Nine current-state surfaces bumped by hand. The classification sweep ran
FIRST, before the first edit: 421 hits on 'v?0.N(.N)' across all tracked
files, each read and sorted current-state vs provenance. Provenance is
untouched -- 'New in v0.4.0', 'measured against 0.3.1', every '0.7.0'
in a code comment or a census candidate name still says what it measured.

The sweep found two surfaces the plan's nine-item list did not name:
README's status BADGE (still 'alpha' -- a version string grep cannot see
it) and ADOPTION-BRIEF's test count, which said 791 against a suite that
runs 792. Both corrected.

pyproject also moves Development Status :: 3 - Alpha -> 5 -
Production/Stable, likewise invisible to a version grep.

CHANGELOG [1.0.0] references [0.3.0] and [0.3.1] for the behaviour
changes rather than repeating them, and carries the freeze point itself:
what is frozen (the exported surface), what is deliberately NOT (all
detection calibration), the three conceded limitations, the one known
open defect (:43), and the runtime-coverage gap -- no external consumer
has run 0.7.0.

No code changed. Per docs/PLAN-v1.md the release gate is the whole suite
green, not a new test: 792 passed, coverage matrix 129/129 + 6/6, exit 0.

src/llm_ingestion_guard/__init__.py

@@ -63,7 +63,7 @@ from .grounding import (
 )
 from . import okf
 
-__version__ = "0.7.0"
+__version__ = "1.0.0"
 
 
 # --- §6 bookends: the two library-side halves around the transform ---------