feat(research): 0106 tasks 1-9 — document layer, content-id move, stores + referential tier

The aura-research leaf crate: ProcessDoc/CampaignDoc with strict parsing
(hand-rolled StageBlock deserializer — deny_unknown_fields does not compose
with internally-tagged enums; Axis declares its ScalarKind once with bare
values, per the #189 user veto), canonical form + content_id_of (the
SHA-256 primitive moved from aura-cli, which now delegates — the id pin set
incl. the independent sweep-store recompute stayed green untouched),
intrinsic validation for both document types (P1 constraints structural),
and the introspection contract (schema tables single-source parse
strictness AND vocabulary/describe/open-slots — the Blockly litmus made
checkable). aura-registry: content-addressed processes/ + campaigns/
stores on the blueprint-store pattern (Ok(None) treat-as-empty) and the
referential tier (validate_campaign_refs: process/strategy refs incl.
identity-scan, axis-name + declared-kind checks against param_space).

Plan deviations, verified by hand and folded back into the plan file:
- Task 9's fixture could not use aura-composites as planned: every shipped
  composite with an open param routes through LinComb, which the zero-arg
  std_vocabulary roster deliberately excludes, so none round-trips through
  blueprint_from_json with the by-type-name resolver. The test hand-builds
  a minimal Bias composite instead (generic over param_space, as planned);
  the unused pro-forma aura-composites dev-dep from the repair pass is
  dropped. This is why the loop reported task 9 BLOCKED
  (review-loop-exhausted on the literal code block); the tree itself is
  complete and green.
- A plan-verbatim test assertion false-matched ("deflate" as substring of
  "deflated-positive"); tightened to the JSON key.
- OpenSlot doc comment backticked (rustdoc read strategies[0] as a link;
  doc gate back to 0 warnings).

Verification: cargo test --workspace 898/0; clippy -D warnings clean;
cargo doc --no-deps 0 warnings. Tasks 10-12 (CLI verb families, final
gates) follow.

refs #189

Cargo.toml

@@ -17,6 +17,7 @@ members = [
     "crates/aura-cli",
     "crates/aura-ingest",
     "crates/aura-registry",
+    "crates/aura-research",
 ]
 
 [workspace.package]