📝 Move knip + outdated to a maintain: prefix

`npm run check` should be the fast, offline correctness ladder only (tsc +
oxlint + oxfmt + cspell, ~3s), so an agent can run it as a confirmation gate
during feature work. check:knip / check:outdated were advisory whole-project /
network scans, and check-outdated exits non-zero whenever any dep is behind.
Keeping them in check made `npm run check` (and the CI build gate) fail on
dependency freshness, which must not block an unrelated feature PR.

Rename them to maintain:knip / maintain:outdated, aggregate under `npm run
maintain`, and run it in CI as a dedicated non-blocking job (continue-on-error)
that surfaces findings without ever gating a merge. Update the script-prefix
convention, the feedback-tier table, and AGENTS.md: the agent may now run
`npm run check`; only `maintain` stays out of the feature loop.

package.json

@@ -35,10 +35,8 @@
     },
     "scripts": {
         "build": "tsc -p tsconfig.build.json",
-        "check": "npm run check:tsc && npm run check:oxlint && npm run check:oxfmt && npm run check:cspell && npm run check:knip && npm run check:outdated",
+        "check": "npm run check:tsc && npm run check:oxlint && npm run check:oxfmt && npm run check:cspell",
         "check:cspell": "cspell lint ${LEFTHOOK_FILES:-.}",
-        "check:knip": "knip --include dependencies,exports,files",
-        "check:outdated": "check-outdated --ignore-pre-releases --ignore-packages @oxfmt/binding-darwin-arm64,@oxfmt/binding-darwin-x64,@oxfmt/binding-linux-arm64-gnu,@oxfmt/binding-linux-arm64-musl,@oxfmt/binding-linux-x64-gnu,@oxfmt/binding-linux-x64-musl,@oxfmt/binding-win32-x64-msvc,@oxlint/binding-darwin-arm64,@oxlint/binding-darwin-x64,@oxlint/binding-linux-arm64-gnu,@oxlint/binding-linux-arm64-musl,@oxlint/binding-linux-x64-gnu,@oxlint/binding-linux-x64-musl,@oxlint/binding-win32-x64-msvc,@oxlint-tsgolint/darwin-arm64,@oxlint-tsgolint/darwin-x64,@oxlint-tsgolint/linux-arm64,@oxlint-tsgolint/linux-x64,@oxlint-tsgolint/win32-arm64,@oxlint-tsgolint/win32-x64",
         "check:oxfmt": "oxfmt --check ${LEFTHOOK_FILES:-.}",
         "check:oxlint": "oxlint ${LEFTHOOK_FILES:-src}",
         "check:tsc": "tsc",
@@ -46,6 +44,9 @@
         "fix": "npm run fix:oxlint && npm run fix:oxfmt",
         "fix:oxfmt": "oxfmt ${LEFTHOOK_FILES:-.}",
         "fix:oxlint": "oxlint --fix src",
+        "maintain": "npm run maintain:knip && npm run maintain:outdated",
+        "maintain:knip": "knip --include dependencies,exports,files",
+        "maintain:outdated": "check-outdated --ignore-pre-releases --ignore-packages @oxfmt/binding-darwin-arm64,@oxfmt/binding-darwin-x64,@oxfmt/binding-linux-arm64-gnu,@oxfmt/binding-linux-arm64-musl,@oxfmt/binding-linux-x64-gnu,@oxfmt/binding-linux-x64-musl,@oxfmt/binding-win32-x64-msvc,@oxlint/binding-darwin-arm64,@oxlint/binding-darwin-x64,@oxlint/binding-linux-arm64-gnu,@oxlint/binding-linux-arm64-musl,@oxlint/binding-linux-x64-gnu,@oxlint/binding-linux-x64-musl,@oxlint/binding-win32-x64-msvc,@oxlint-tsgolint/darwin-arm64,@oxlint-tsgolint/darwin-x64,@oxlint-tsgolint/linux-arm64,@oxlint-tsgolint/linux-x64,@oxlint-tsgolint/win32-arm64,@oxlint-tsgolint/win32-x64",
         "test": "npm run check:tsc && node --test --strip-types \"src/**/*.test.ts\"",
         "test:ci": "c8 --reporter=text --reporter=lcov --reporter=html node --test --strip-types \"src/**/*.test.ts\"",
         "test:unit": "node --test --strip-types \"src/**/*.test.ts\"",