refactor(ci): extract large inline scripts to scripts/ci/ (#587)

The CI workflow contained a ~90-line bash script for change-detection
(lines 38-128) and a ~80-line JavaScript block for lint feedback
(lines 292-370) directly inline in the YAML. Large inline scripts are
harder to test, lint, and maintain than standalone files.

Extract:
- Change-detection logic → scripts/ci/detect_change_scope.sh
- Lint feedback logic → scripts/ci/lint_feedback.js

The workflow now calls these external scripts. GitHub expression values
that were previously interpolated inline are passed as environment
variables instead.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

scripts/ci/lint_feedback.js

@@ -0,0 +1,90 @@
+// Post actionable lint failure summary as a PR comment.
+// Used by the lint-feedback CI job via actions/github-script.
+//
+// Required environment variables:
+//   RUST_CHANGED      — "true" if Rust files changed
+//   DOCS_CHANGED      — "true" if docs files changed
+//   LINT_RESULT       — result of the lint job
+//   LINT_DELTA_RESULT — result of the strict delta lint job
+//   DOCS_RESULT       — result of the docs-quality job
+
+module.exports = async ({ github, context, core }) => {
+  const owner = context.repo.owner;
+  const repo = context.repo.repo;
+  const issueNumber = context.payload.pull_request?.number;
+  if (!issueNumber) return;
+
+  const marker = "<!-- ci-lint-feedback -->";
+  const rustChanged = process.env.RUST_CHANGED === "true";
+  const docsChanged = process.env.DOCS_CHANGED === "true";
+  const lintResult = process.env.LINT_RESULT || "skipped";
+  const lintDeltaResult = process.env.LINT_DELTA_RESULT || "skipped";
+  const docsResult = process.env.DOCS_RESULT || "skipped";
+
+  const failures = [];
+  if (rustChanged && !["success", "skipped"].includes(lintResult)) {
+    failures.push("`Lint Gate (Format + Clippy)` failed.");
+  }
+  if (rustChanged && !["success", "skipped"].includes(lintDeltaResult)) {
+    failures.push("`Lint Gate (Strict Delta)` failed.");
+  }
+  if (docsChanged && !["success", "skipped"].includes(docsResult)) {
+    failures.push("`Docs Quality` failed.");
+  }
+
+  const comments = await github.paginate(github.rest.issues.listComments, {
+    owner,
+    repo,
+    issue_number: issueNumber,
+    per_page: 100,
+  });
+  const existing = comments.find((comment) => (comment.body || "").includes(marker));
+
+  if (failures.length === 0) {
+    if (existing) {
+      await github.rest.issues.deleteComment({
+        owner,
+        repo,
+        comment_id: existing.id,
+      });
+    }
+    core.info("No lint/docs gate failures. No feedback comment required.");
+    return;
+  }
+
+  const runUrl = `${context.serverUrl}/${owner}/${repo}/actions/runs/${context.runId}`;
+  const body = [
+    marker,
+    "### CI lint feedback",
+    "",
+    "This PR failed one or more fast lint/documentation gates:",
+    "",
+    ...failures.map((item) => `- ${item}`),
+    "",
+    "Open the failing logs in this run:",
+    `- ${runUrl}`,
+    "",
+    "Local fix commands:",
+    "- `./scripts/ci/rust_quality_gate.sh`",
+    "- `./scripts/ci/rust_strict_delta_gate.sh`",
+    "- `./scripts/ci/docs_quality_gate.sh`",
+    "",
+    "After fixes, push a new commit and CI will re-run automatically.",
+  ].join("\n");
+
+  if (existing) {
+    await github.rest.issues.updateComment({
+      owner,
+      repo,
+      comment_id: existing.id,
+      body,
+    });
+  } else {
+    await github.rest.issues.createComment({
+      owner,
+      repo,
+      issue_number: issueNumber,
+      body,
+    });
+  }
+};