Promote schema and canonicalizer out of history; add EvidenceModel (T06)

Verified the three published hashes reproduce byte for byte before promoting
anything, then moved the schema, canonicalizer and vectors into governed assets.
history/20260909-initial-exploration/ is untouched and stays the provenance
record.

- schemas/, informed_decision/, tests/vectors/ populated; the reference
  canonicalizer's ad-hoc __main__ block replaced by a real
  `python -m informed_decision` entry point.
- tests/test_canonicalize.py — 20 tests, all green. Published vectors, all four
  isolation properties, canonical-form round-trip, key sorting, and a provenance
  test asserting the governed fixtures have not drifted from history/.
- docs/specs/EvidenceModel.md — the two hashes, the split and why it exists, the
  four isolation properties, the presentation record, the bundle, and the
  relationship to audit-core.
- pyproject.toml, Makefile.

One test of mine was wrong on first run: it scanned for ", " to assert no
insignificant whitespace, which fires on prose inside a brief. Replaced with a
canonical round-trip comparison, which is the property actually meant. The
canonicalizer was correct.

EvidenceModel leads with what the model does NOT claim — no proof of
comprehension, no proof of reading (deliberately, since the alternative is
surveillance), no survival of a compromised surface, and audit-core's inherited
bound that a hash chain cannot prove a record was never sent.

T06 stays progress: the SCOPE.md rewrite is gated on the T02 ruling.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01V3W1dQG7GFFM9d94jFx7iR

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 1565372@bnt-lap001
Assistant-Session: 16bb2f25-b34c-49ef-8e94-5fec3567a568

informed_decision/__main__.py

@@ -0,0 +1,31 @@
+"""CLI: compute a view_hash or awareness_hash over a document.
+
+    python -m informed_decision <path.json> [view|awareness]
+"""
+
+from __future__ import annotations
+
+import json
+import pathlib
+import sys
+
+from .canonicalize import awareness_hash, view_hash
+
+
+def main(argv: list[str]) -> int:
+    if not argv:
+        print(__doc__, file=sys.stderr)
+        return 2
+    data = json.loads(pathlib.Path(argv[0]).read_text(encoding="utf-8"))
+    kind = argv[1] if len(argv) > 1 else "view"
+    if kind not in ("view", "awareness"):
+        print(f"unknown kind {kind!r}; expected 'view' or 'awareness'", file=sys.stderr)
+        return 2
+    result = view_hash(data) if kind == "view" else awareness_hash(data)
+    print(result["canonical"])
+    print(result["hex"])
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main(sys.argv[1:]))