Add Fortran/Fypp static analysis linter to catch copy-paste bugs #1211
Description
Feature Request
Add a Python-based static analysis linter for Fortran/Fypp source code that catches patterns known to cause silent bugs. Integrate it into the pre-commit hook (`./mfc.sh precheck`) and CI (`lint-source.yml`).
Proposed Checks
| Check | What it catches |
|---|---|
| Fypp list duplicates | Duplicate entries in `#:for VAR in [...]` broadcast/loop lists |
| Duplicate consecutive lines | Identical adjacent non-trivial lines (copy-paste errors) |
| Hardcoded byte size | `int(8._wp, ...)` patterns that assume 8-byte reals |
These checks are motivated by real bugs found in the codebase. The linter would prevent regressions after the bugs are fixed.