The owner sets the table height (tableOffsetMm, -100..100 mm) in a field on /admin, saved through PUT /settings by the page's one hashed script #325

Replaces #279 (from #163). Pulls #307 and #315 carried the same commit, 59b9aea. Its deploy failed on one test, the viewer's first-visit gzip budget (51,209 bytes against 51,200), and that is a file the pull never touched: the old base was over budget. Current main passes all 570 tests. Since then, main's /admin has gained a hashed inline script (HEALTH_SCRIPT in src/admin-page.ts) and connect-src 'self', so #307's second script and its CSP edit no longer fit.

Start from current main. You may reuse the field, test and README text from 59b9aea (refs/pull/307/head). Do not reuse its CSP or lobby.test.ts edits.

Done:

• [ ] The owner's /admin has a "Table height" number field for tableOffsetMm (-100..100, step 1) with a Save button. It loads the current value with GET /settings and saves with a same-origin PUT /settings, and it shows the saved value or the server's error text. A moderator gets neither the field nor the code that saves it.
• [ ] The page still has exactly one inline script. Extend HEALTH_SCRIPT, or add one script that replaces it, and keep ADMIN_CSP's single sha256 pinned to it. No unsafe-inline and no new CSP sources.
• [ ] src/viewer.html and the page's modules are untouched, so the first-visit gzip budget is unchanged.
• [ ] src/admin-page.test.ts checks: the field is present for the owner and absent for a moderator, there is one <script tag, and its hash matches the CSP.
• [ ] Software/README.md says where to set the table height. forge.json is untouched. tsc --noEmit and bun --cwd Software/so101 test pass, and the preview deploys.