feat(P2): Nova rebrand — code/env-vars/consumer-path (REQ-158/159/160)

core/env.py dual-read helper (D-108); 21 ACDL_*→NOVA_* env vars migrated
across core/scripts/adapters/tests/workflows + .env/.env.secrets (key
rename, values stay). G-106 binding: run_platform.sh:288-289 +
regression_verify.py:309-312 dual-read (NOVA first, ACDL fallback).
G-108 binding: Gitea NOVA_* secrets created via API + workflow secrets:
refs updated (deploy.yml + modules-lifecycle.yml, .gitea + .github).
acdl_tagging.py→nova_tagging.py (D-109 warn mode, nova:* enforced).
.acdl/→.nova/ consumer path (resolver + deploy workflow + schema +
tests + docs). Test fixtures updated; pytest + run_ci.sh PASS.

---ci---
project: acdl
phase: 2
milestone: v1.15
status: execute
---/ci---

docs/index.md

@@ -18,7 +18,7 @@ There are two kinds of repository in the Nova model:
   and the reusable workflow files. Platform engineers work here. A consumer
   never clones it.
 - **Consumer repo (yours).** A consumer repo contains only its application
-  code, one or more contracts (`.acdl/contract.yml`), and one or more CI
+  code, one or more contracts (`.nova/contract.yml`), and one or more CI
   definitions (a thin `.github/workflows/deploy.yml` that `uses:` the central
   reusable workflow, pointing at the appropriate environment + contract).
   The consumer does not write infrastructure modules, workflow YAML, or