feat(P1): remove gitea/gitlab from synced files + simplify docs (REQ-230,231,232)

Genericize forge-detection code: gitea→forge/generic_forge, GITEA_ACTOR→FORGE_ACTOR.
Drop .gitea byte-identity test assertions (keep GitHub-side + contract conformance).
Add test_no_forge_mentions.py guard test (REQ-230).
Delete completed migration docs (NOVA_MIGRATION.md, NOVA_AWS_MIGRATION.md).
Move NO_HUMANS_THESIS.md to .ciagent/ (internal artifact).
Strip ciagent-internal provenance from synced docs (REQ-/D-/P-/CAP- IDs,
milestone headers, .ciagent/PROJECT.md citations).
Trim README.md (reusable deploy section, local key rotation paragraph).
Fix version-tag drift (@v1.13→@v1.19, acdl/→nova/).

---ci---
project: acdl
phase: 1
milestone: v1.20
status: execute
requirements: [REQ-230, REQ-231, REQ-232]
---/ci---

tests/test_deploy_workflow_env_input.py

@@ -1,6 +1,6 @@
 """REQ-106: deploy workflow environment input + run_platform.sh --environment.
-Both deploy workflows (Gitea + GitHub) declare the environment input,
-are byte-identical, and the resolver supports environment_override.
+The deploy workflow declares the environment input and the resolver
+supports environment_override.
 """
 import sys
 from pathlib import Path
@@ -11,16 +11,10 @@ sys.path.insert(0, str(ROOT))
 from core.contract_resolver import resolve
 
 GITHUB = ROOT / ".github" / "workflows" / "deploy.yml"
-GITEA = ROOT / ".gitea" / "workflows" / "deploy.yml"
 
 
-def test_both_deploy_workflows_exist():
+def test_deploy_workflow_exists():
     assert GITHUB.is_file()
-    assert GITEA.is_file()
-
-
-def test_deploy_workflows_byte_identical():
-    assert GITHUB.read_text() == GITEA.read_text(), "deploy workflows must be byte-identical"
 
 
 def test_deploy_workflow_has_environment_input():
@@ -39,7 +33,7 @@ def test_deploy_workflow_passes_env_flag_to_run_platform():
 
 
 def test_resolver_environment_override_changes_env():
-    """D-088: environment_override changes the resolved environment."""
+    """environment_override changes the resolved environment."""
     stack = resolve(str(ROOT / "contracts" / "static-assets.yml"),
                     environment_override="qa")
     s3 = [r for r in stack["resources"] if r["type"] == "aws:s3:bucket"][0]
@@ -78,7 +72,5 @@ def test_run_platform_sh_has_environment_flag():
     text = (ROOT / "scripts" / "run_platform.sh").read_text()
     assert "--environment" in text
     assert "ENVIRONMENT_OVERRIDE" in text
-    # P3 (REQ-167): NOVA_* only; the dead ACDL_ENVIRONMENT_OVERRIDE export
-    # (comment said "removed in P5" but the line was present) is gone.
     assert "NOVA_ENVIRONMENT_OVERRIDE" in text
-    assert "ACDL_ENVIRONMENT_OVERRIDE" not in text
+    assert "ACDL_ENVIRONMENT_OVERRIDE" not in text