🚚 Rename publint script to publish:publint and document prefix convention

publint validates the publishable artifact (dist/ vs package.json),
not the source. It should run only at publish time, in the CI publish
job, not on every commit.

- Rename check:publint -> publish:publint
- Remove from 'check' chain
- Add 'publish:publint' as a step in the CI publish job, right
  before 'npm publish'
- Introduce a 'publish:' script prefix for publish-time-only scripts
- Document the prefix convention (check:, fix:, test:, publish:)
  in project-specs.md (as a top-level subsection under Scripts)
  and in the README
- Add 'publint' and 'stricter' to cspell word list

A new script should pick the prefix that matches its lifecycle, not
invent a new one. The 'publish:' prefix has no 'npm run publish'
aggregator by design (publishing is CI-only).

cspell.json

@@ -15,7 +15,9 @@
         "typescriptteam",
         "gitmoji",
         "dbaeumer",
-        "msvc"
+        "msvc",
+        "publint",
+        "stricter"
     ],
     "ignorePaths": ["dist", "node_modules", "coverage", "*.svg", ".gitignore"]
 }