ci: matrix over Node 22 and 24, add the bench and packaging tiers (task 0040)

The workflow pinned Node 20, which reached end-of-life in April 2026, while
the manifest promised support down to it — so the entire claimed range below
the single tested version went unverified and its floor was unsupported.

Matrix over the two supported long-term-support majors and narrow the engine
range to `^22 || ^24`, naming exactly what is tested. Narrowing is free now
because nothing has been published and no tags exist.

The benchmark harness tier joins every leg: it is deterministic and needs no
network, and its non-default runner configuration made it easy to believe it
was running when it was not. The end-to-end and packaging tiers run on the
highest leg only, conditioned on a flag attached to that leg through a matrix
`include` entry rather than on a version number restated at each site. The
benchmark smoke tier stays out, since it would pass by skipping.

`@types/node` follows the new floor; it was the last Node 20 reference in the
manifest, and the typecheck runs on every leg.

package-lock.json

@@ -17,14 +17,14 @@
         "gitea-axi": "dist/main.js"
       },
       "devDependencies": {
-        "@types/node": "^20.19.0",
+        "@types/node": "^22.20.1",
         "@vitest/coverage-v8": "^3.2.7",
         "tsx": "^4.23.1",
         "typescript": "^5.8.0",
         "vitest": "^3.2.0"
       },
       "engines": {
-        "node": ">=20"
+        "node": "^22 || ^24"
       },
       "peerDependencies": {
         "@anthropic-ai/claude-agent-sdk": ">=0.3.0"
@@ -1050,9 +1050,9 @@
       "license": "MIT"
     },
     "node_modules/@types/node": {
-      "version": "20.19.43",
-      "resolved": "https://registry.npmjs.org/@types/node/-/node-20.19.43.tgz",
-      "integrity": "sha512-6oYBAi5ikg4Pl+kGsoYtawUMBT2zZMCvPNF7pVLnHZfd1zf38DRiWn/gT01RYCdUqkv7Fhr+C9ot4/tb+2sVvA==",
+      "version": "22.20.1",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-22.20.1.tgz",
+      "integrity": "sha512-EANqOCF9QFyra+4pfxUcX9STKJpCLjMbObVzljIJomAWSnuSIEAvyzEU53GaajbXJEgdh0iEcPL+DGvpUd4k1Q==",
       "dev": true,
       "license": "MIT",
       "dependencies": {