feat: add auto-merge for non-major dependency updates

Minori now automatically merges dependency update PRs when:
- The update is NOT a major version bump (to avoid breaking changes)
- The CI checks pass (status = "success")
- An existing PR for the dependency update is found

This reduces manual work for safe, non-breaking dependency updates
whilst still requiring human review for potentially breaking changes.

Changes:
- Add version comparison utility to detect major version bumps
- Add Gitea service methods for commit status and PR merging
- Add auto-merge logic to update orchestrator
- Add comprehensive tests for new functionality

test/utils/versionComparison.spec.ts

@@ -0,0 +1,108 @@
+/**
+ * @copyright NHCarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+
+/* eslint-disable vitest/valid-expect -- Test expectations don't need messages */
+/* eslint-disable max-lines-per-function -- Test suites naturally have many cases */
+/* eslint-disable max-nested-callbacks -- Vitest structure requires nesting */
+/* eslint-disable vitest/prefer-to-be-truthy -- toBe(true) is clearer for boolean functions */
+/* eslint-disable vitest/prefer-to-be-falsy -- toBe(false) is clearer for boolean functions */
+
+import { describe, expect, it } from "vitest";
+import {
+  isMajorVersionBump,
+  stripVersionPrefix,
+} from "../../src/utils/versionComparison.js";
+
+describe("versionComparison", () => {
+  describe("stripVersionPrefix", () => {
+    it("should strip caret prefix", () => {
+      expect.assertions(1);
+      expect(stripVersionPrefix("^1.2.3")).toBe("1.2.3");
+    });
+
+    it("should strip tilde prefix", () => {
+      expect.assertions(1);
+      expect(stripVersionPrefix("~1.2.3")).toBe("1.2.3");
+    });
+
+    it("should strip greater than prefix", () => {
+      expect.assertions(1);
+      expect(stripVersionPrefix(">1.2.3")).toBe("1.2.3");
+    });
+
+    it("should strip less than prefix", () => {
+      expect.assertions(1);
+      expect(stripVersionPrefix("<1.2.3")).toBe("1.2.3");
+    });
+
+    it("should strip equals prefix", () => {
+      expect.assertions(1);
+      expect(stripVersionPrefix("=1.2.3")).toBe("1.2.3");
+    });
+
+    it("should strip multiple prefix characters", () => {
+      expect.assertions(1);
+      expect(stripVersionPrefix(">=1.2.3")).toBe("1.2.3");
+    });
+
+    it("should return version without prefix unchanged", () => {
+      expect.assertions(1);
+      expect(stripVersionPrefix("1.2.3")).toBe("1.2.3");
+    });
+  });
+
+  describe("isMajorVersionBump", () => {
+    it("should detect major version bump", () => {
+      expect.assertions(1);
+      expect(isMajorVersionBump("1.2.3", "2.0.0")).toBe(true);
+    });
+
+    it("should detect major version bump with prefixes", () => {
+      expect.assertions(1);
+      expect(isMajorVersionBump("^1.2.3", "^2.0.0")).toBe(true);
+    });
+
+    it("should not detect minor version bump as major", () => {
+      expect.assertions(1);
+      expect(isMajorVersionBump("1.2.3", "1.3.0")).toBe(false);
+    });
+
+    it("should not detect patch version bump as major", () => {
+      expect.assertions(1);
+      expect(isMajorVersionBump("1.2.3", "1.2.4")).toBe(false);
+    });
+
+    it("should handle version with pre-release tags", () => {
+      expect.assertions(1);
+      expect(isMajorVersionBump("1.2.3", "2.0.0-beta.1")).toBe(true);
+    });
+
+    it("should return false for invalid from version", () => {
+      expect.assertions(1);
+      expect(isMajorVersionBump("invalid", "2.0.0")).toBe(false);
+    });
+
+    it("should return false for invalid to version", () => {
+      expect.assertions(1);
+      expect(isMajorVersionBump("1.2.3", "invalid")).toBe(false);
+    });
+
+    it("should return false for both invalid versions", () => {
+      expect.assertions(1);
+      expect(isMajorVersionBump("invalid", "also-invalid")).toBe(false);
+    });
+
+    it("should handle 0.x.x to 1.x.x as major bump", () => {
+      expect.assertions(1);
+      expect(isMajorVersionBump("0.9.5", "1.0.0")).toBe(true);
+    });
+
+    it("should not detect same version as major bump", () => {
+      expect.assertions(1);
+      expect(isMajorVersionBump("1.2.3", "1.2.3")).toBe(false);
+    });
+  });
+});