Feature ETP-4603: Add multiField generator, F18 validator and neoImage hook

[valenvivaldi]

⚠️ BLOCKED — merge order. The core PR etendosoftware/etendo_core#1101 (etendosoftware/etendo_core#1101) MUST be merged FIRST. Do NOT merge this PR until #1101 is merged.

ETP-4603 — multiField tooling (core)

Core support for the multiField composite list column.

Changes (core repo)

• generate-frontend.js / generate-contract.js / resolve-curated.js: emit and carry the multiField decorator; per-part resolution, absorbed-column suppression, escaping fix on generated key/column.
• New validator rule F18: blocks on non-existent subtitle/media/part fields and on non-queryable sort parts/host (no-op for windows without multiField).
• Moved generic useNeoImage hook + box-icon into @etendosoftware/app-shell-core (with barrel/exports) so functional windows consume them via shims.

Verification

• Generator tests + F18 fixtures green.

Companion to the functional PR in schema_forge. This is the package the functional repo pins (preview build).

🤖 Generated with Claude Code

[sonarscanetendo]

Quality Gate passed

Issues

• 0 New Issues
• 0 Fixed Issues
• 0 Accepted Issues

Measures

• 0 Security Hotspots
• 0.00% Coverage (0.00% Estimated after merge)
• 0.00% Duplicated Code (0.50% Estimated after merge)

Project ID: etendosoftware_schema_forge_core_976a1e0b-4b24-4757-a2f4-8afa9a5e0289

View in SonarQube

[github-actions]

📦 Preview packages published — dist-tag alpha

0.3.17-preview.feature-ETP-4603.20260724152158.1595f71

To exercise the published-package path (no LOCAL_CORE), bump all
core pins to this preview in the functional repo and reinstall:

make bump-core-version VERSION=0.3.17-preview.feature-ETP-4603.20260724152158.1595f71

Re-posted on each push to this branch; supersedes older previews.