[codex] fix extract-knowhow report template generation

[ktwu01]

What changed

• fix the extract-knowhow report template so the JSON placeholder appears only in the const DATA = __REPORT_DATA__; assignment
• correct the report form to populate institution from DATA.institution
• add a regression test that checks the template placeholder and institution binding invariants
• tighten the command instructions so generation replaces only the DATA token and preserves the rest of the template verbatim

Why

Generated reports could become invalid HTML/JS when placeholder replacement also touched the explanatory comment in the template, leaving duplicated JSON and stray text in the script block. The template also incorrectly filled the institution field from DATA.email.

Impact

This makes generated ~/.openscientist/report.html files more reliable, preserves the interactive review UI, and fixes the author institution field in the browser form.

Validation

• npm test
• rendered the template with sample JSON and verified the inline script parses successfully