Add a Jev code grader for source and spec files

CLAUDE.md

@@ -456,6 +456,34 @@ bin/coverage_check app/controllers/users_controller.rb
 - **Priority files**: Controllers, services, models with business logic
 - **Low coverage files**: Immediate attention required for < 80% coverage
 
+### Code Quality Grading
+
+**Jev Grader** (`bin/grade-code`) - scores source and spec files against the
+house rules with Jev, one file per call. No mechanical checks: those are
+CodeStandardsChecker, standardrb and `bin/lint`.
+
+- **Usage**: `bin/grade-code [files or dirs]` - defaults to `app spec lib`
+- **Single file**: prints the full per-check report; **2+ files**: worst-first
+  ranked table with the most-failed checks across the batch
+
+```bash
+bin/grade-code                                  # whole source and test tree
+bin/grade-code app/models --workers 6           # parallel sweep of a directory
+bin/grade-code --kinds model,controller         # only these kinds
+bin/grade-code app/models/inspection.rb         # one file in detail
+bin/grade-code spec --limit 20 --csv tmp/grades.csv # first 20, written to CSV
+bin/grade-code --list-checks                    # the rubric
+```
+
+- **What it scores**: idiomatic Rails, nice simple methods, short comments that
+  explain WHY with no history notes, plain technical English, no dead code or
+  defensive fallbacks, I18n for user-facing strings, semantic HTML, form
+  partial conventions, and for specs: not tautological, succinct names, happy
+  path plus edge cases
+- **Needs** `OPENCODE_API_KEY` (or `/run/secrets/opencode_api_key`, or `.env`)
+- **Cost**: ~80s for the whole 560-file tree at `--workers 6`; advisory only,
+  nothing is blocked on the score
+
 ### Code Organization
 
 - **Create partials for repeated code** - DRY principle