ESLint debt: 59 errors blocking strict CI gating

[stultus]

Context

The new CI workflow (PR #208) added npm run lint enforcement, but the codebase has 59 pre-existing eslint errors. To unblock the cross-platform CI rollout, eslint runs with continue-on-error: true — it's visible in the run summary but doesn't fail the job. This issue tracks the cleanup needed to flip that flag.

Breakdown

After running npx eslint . --fix (which auto-resolved 1 of 60), the remaining errors are:

Count	Rule	Difficulty	Notes
14	@typescript-eslint/no-unused-vars	Easy	Remove imports or _ prefix
13	svelte/no-unused-svelte-ignore	Easy	Just delete the stale comments
12	svelte/prefer-svelte-reactivity	Hard	Svelte 5 runes migration ($state, etc.)
10	svelte/require-each-key	Medium	Add stable key per {#each} block
5	@typescript-eslint/no-unused-expressions	Medium	Inspect each — could be intent or bug
2	svelte/no-dom-manipulating	Medium	Refactor direct DOM access
2	svelte/no-at-html-tags	Security	Audit {@html} usage for XSS
1	no-control-regex	Medium	Review the regex in question

Suggested cleanup order

1. Mechanical pass (deletes + renames): unused-vars, unused-svelte-ignore, prefer-const. Low risk, big visual win (~28 errors).
2. Each-block keys: pick stable keys per loop (likely id or index). ~10 errors.
3. {@html} audit: confirm each call site only renders trusted content; switch to safe alternatives where possible. Do this before any prefer-svelte-reactivity migration touches the same files. ~2 errors.
4. Unused-expressions + control-regex + dom-manipulating: case-by-case. ~8 errors.
5. Svelte 5 reactivity migration: 12 errors, riskiest. Bundle with related rendering changes if any.

Done when

.github/workflows/ci.yml has continue-on-error: true removed from the ESLint step, the CI gate is strict, and PRs fail on new lint regressions.