chore(deadcode): ratchet down the 85 pre-existing unused exports/types (follow-up to #607)

Follow-up to #607 (PR #673).

After #673 re-greened the dead-code ratchet, the knip baseline holds at **85** — all of it pre-existing drift, no longer masked by the devDep/false-positive noise:

| category | count |
|---|---|
| \`exports\` | 44 |
| \`types\` | 41 |

## Why this matters

The ratchet job (\`check:deadcode-ratchet\`) is **advisory / non-blocking** today (\`continue-on-error: true\`). Its stated milestone is to *"flip to blocking once the baseline is driven to zero."* Because it is non-blocking, roughly 7 genuine unused export/type regressions drifted into \`main\` unnoticed inside the +13 that #607 reconciled. Every merge that adds dead code under a non-blocking gate pushes the flip-to-blocking milestone further out.

## Ask

Chip the 85 down over one or more scoped PRs, lowering \`knip-baseline.json\` \`count\` in the same PR each time to lock in the gain (per the baseline's own guidance). Removing unused exports/types requires per-symbol analysis — some may be public API surface or referenced dynamically — so this is deliberately **not** a single bulk-delete.

Reproduce the current list:

\`\`\`
node_modules/.bin/knip --reporter json | jq '[.issues[] | {file, exports: (.exports // [] | map(.name)), types: (.types // [] | map(.name))}] | map(select((.exports|length)>0 or (.types|length)>0))'
\`\`\`

Once the count reaches 0, drop \`continue-on-error: true\` from the ratchet CI job to make it blocking.

Beginne mit dem Lesen von knip-baseline.json und führe den bereitgestellten knip-Befehl aus, um die 85 ungenutzten Exporte und Typen zu untersuchen. Überprüfe die Referenzen jedes Symbols, bevor du die zugehörige Quelldatei änderst, und aktualisiere die Baseline-Zählung mit jeder abgegrenzten Bereinigung. Erledigt ist die Aufgabe, wenn die Zählung 0 erreicht und continue-on-error: true aus dem ratchet-CI-Job entfernt wurde.

Vom Indexierungsmodell aus dem Issue-Text verfasst.