feat: correction notes on every sprite regeneration surface, not just turnaround and anchors

[atomantic]

Summary

Extends the sprite correction-prompt pattern (shipped for the turnaround sheet and the 7 directional anchors in #2964/#2979) to the five regeneration surfaces that could still only be re-rolled blind: the main reference, a place/object's ambient reference, and the walk-cycle / scanner-action / ambient-loop videos.

Server

• services/sprites/prompts.js grows one shared correctionClause(text, subject) that every builder appends last, replacing the two hand-inlined copies. buildMainReferencePrompt, buildAmbientReferencePrompt, buildWalkVideoPrompt, and buildAmbientVideoPrompt each take an optional correctionPrompt.
• scannerPrompt is promoted out of services/sprites/scanner.js into prompts.js as buildScannerPrompt (wording unchanged, so an existing scanner run's rebuilt provenance still matches what was sent). That also fixes a latent provenance bug: assetPrompt.js was rebuilding scanner runs with the walk builder, reporting a prompt that was never sent. Each track now rebuilds with its own builder and reports source: 'scanner'.
• spriteWalkGenerateSchema / spriteScannerGenerateSchema / spriteAmbientGenerateSchema take correctionPrompt: z.string().max(4000).optional() (the reference schema already had it). Each service trims it, threads it into the prompt, and stamps it on the run record / job tag only when non-empty, mirroring the existing anchor branch.
• assetPrompt.js threads correctionPrompt through both the candidate-sidecar rebuild and the animation-run rebuild, so a corrected re-roll's provenance shows the correction that produced it.

Client

• New pure client/src/lib/spriteCorrections.js owns the correction-map key vocabulary plus correctionPromptPayload (moved from CorrectionNote.jsx, which re-exports it), so the pure gating layer can share the keys without importing a component. Barrel + README rows added.
• CorrectionNote.jsx gains CorrectionNoteToggle / CorrectionToggleButton — the collapsed-pill-plus-note affordance the new surfaces use, and the same button the asset card was hand-rolling.
• ReferenceWorkflow.jsx (main branch, previously hardcoded to {}), WalkWorkflow.jsx, ScannerWorkflow.jsx, and AmbientWorkflow.jsx (both its reference and loop actions) render the shared note; AssetCollection.jsx's note is no longer gated to kind === 'reference'; Sprites.jsx spreads correctionPromptPayload into all four generators.

One decision recorded on the issue

The plan said to reuse the page-owned map for the walk card. Reusing the bare direction key across surfaces would mean an anchor note ("no pocket on the right sleeve" — a still-image fix) silently riding the next walk video re-roll for that direction. So the map stays single and page-owned (still reset on record switch), but keys are namespaced per surface: anchors keep the bare direction (existing state resolves unchanged), while walk:<dir>, scanner:<dir>, main, ambient-reference, and ambient-loop prefix. Relatedly, buildCollectionActions() returns a correctionKey (mirroring the existing direction) instead of taking a correctionPrompt pass-through, so Sprites.jsx assembles the payload in exactly one place — the way generateAnchor already worked.

Test plan

• cd server && npx vitest run services/sprites — 231 passed. New coverage:
  • prompts.test.js: a table-driven block over all 8 builders asserting one trimmed clause appended last with the right subject noun, and that undefined/null/''/' '/'\n\t '/non-string all produce a prompt byte-identical to the blind regenerate (the hard acceptance criterion), plus direct correctionClause unit tests.
  • walk.test.js / scanner.test.js / ambient.test.js: non-empty case threads into the TUI prompt and stamps the run record; blank case leaves the motion prompt identical and the run record without the key.
  • reference.test.js: main-reference derive (correction + blank), and the ambient main composing an additive correction alongside the full-replace designPrompt.
  • assetPrompt.test.js: each track rebuilds with its own builder (scanner no longer reports the walk prompt), and both a corrected run record and a corrected candidate sidecar rebuild with their clause.
• cd client && npm test — 470 files / 5202 tests passed (full suite). New coverage in CorrectionNote.test.jsx (key namespacing + no cross-surface leakage + the toggle), WalkWorkflow.test.jsx, ScannerWorkflow.test.jsx, a new AmbientWorkflow.test.jsx, AssetCollection.test.jsx (walk-card note), spriteCollectionActions.test.js (correctionKey is walk-namespaced, never the bare direction), and ReferenceWorkflow.test.jsx (main sends the note, omits the field when blank, and does not pick up an anchor note).
• cd server && npm test — 1311 pre-existing failures, all from the absent Postgres in this environment (… requires PostgreSQL). Verified against a clean origin/main worktree: 1309 identical failures, and the 2-file difference (lib/dataRoot.test.js, services/installState.test.js) reproduces in this worktree with the diff stashed — those two are sensitive to the worktree living under the primary repo's data/ tree, not to this change.
• npx eslint clean on every touched client file.

Closes #3134