ci: fix pre-existing failures so PR checks can actually pass

Four CI checks failed on every PR (and on main) for reasons unrelated to
any code change — the "CI that cannot pass" problem. Fix each:

- rust-ci.yml: the job calls the shared reusable rust-ci-reusable.yml with
  no `with:` block, so its required `toolchain` input was empty and the
  "parse toolchain version" step failed with `'toolchain' is a required
  input`. Pass `toolchain: stable` (matches .tool-versions and the
  dtolnay/rust-toolchain pins in e2e.yml).
- tests/aspect/cross_cutting_test.sh: the Documentation check asserted
  README.adoc, but the repo ships README.md (root .adoc is EXPLAINME.adoc).
  Accept either; aspect suite now PASS 29 / FAIL 0.
- cargo-audit.yml create-issue: `needs: audit` + `if: failure()` ran on PR
  events where GITHUB_TOKEN is read-only, so `gh issue create` 403'd. Guard
  with `&& github.event_name != 'pull_request'`; issues are still filed on
  push/schedule runs.

Both workflow files keep their SPDX line-1 header and top-level permissions
block (workflow-linter.yml requirements); YAML validated.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015qwVESTcbfanY2iJPQNoSz

Author: claude

.github/workflows/cargo-audit.yml

@@ -38,7 +38,10 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 15
     needs: audit
-    if: failure()
+    # Only file a tracking issue on push/schedule runs. On pull_request events
+    # GITHUB_TOKEN is forced read-only, so `gh issue create` 403s; guarding here
+    # keeps PR runs green (the audit job itself still gates the PR).
+    if: failure() && github.event_name != 'pull_request'
     permissions:
       issues: write
     steps:

.github/workflows/rust-ci.yml

@@ -15,3 +15,5 @@ permissions:
 jobs:
   rust-ci:
     uses: hyperpolymath/standards/.github/workflows/rust-ci-reusable.yml@d135b05bfc647d0c0fbfedc7e80f37ea50f49236
+    with:
+      toolchain: stable

tests/aspect/cross_cutting_test.sh

@@ -51,7 +51,7 @@ check "No unsafe in reversible-core" "! grep -rh 'unsafe' '${JK_DIR}/crates/reve
 
 # --- Documentation ---
 echo "--- Documentation ---"
-check "README.adoc exists" "[ -f '${JK_DIR}/README.adoc' ]"
+check "README exists" "[ -f '${JK_DIR}/README.md' ] || [ -f '${JK_DIR}/README.adoc' ]"
 check "SECURITY.md exists" "[ -f '${JK_DIR}/SECURITY.md' ]"
 check "ARCHITECTURE.md exists" "[ -f '${JK_DIR}/ARCHITECTURE.md' ]"
 check "PROOF-NEEDS.md exists" "[ -f '${JK_DIR}/PROOF-NEEDS.md' ]"