chore(license): move to PolyForm Noncommercial 1.0.0

The project licence changes from AGPL-3.0 to the PolyForm Noncommercial
License 1.0.0 for this and future versions: free to use, modify and
self-host for noncommercial purposes; commercial use needs a separate
arrangement. Releases up to and including v1.15.18 were published under
AGPL-3.0 and remain available under that licence. LICENSE carries the
verbatim PolyForm text, and the SPDX identifier is updated in
package.json, the version endpoint, the OpenAPI info block, the image
labels and the README.

.github/workflows/docker-publish.yml

@@ -107,7 +107,7 @@ jobs:
           labels: |
             org.opencontainers.image.title=HealthLog
             org.opencontainers.image.description=Self-hosted health-tracking PWA
-            org.opencontainers.image.licenses=AGPL-3.0-only
+            org.opencontainers.image.licenses=PolyForm-Noncommercial-1.0.0
             org.opencontainers.image.source=https://github.com/${{ github.repository }}
 
       # v1.4.27 B3 — GeoLite2-City + GeoLite2-ASN databases are too large
@@ -299,7 +299,7 @@ jobs:
           labels: |
             org.opencontainers.image.title=HealthLog
             org.opencontainers.image.description=Self-hosted health-tracking PWA
-            org.opencontainers.image.licenses=AGPL-3.0-only
+            org.opencontainers.image.licenses=PolyForm-Noncommercial-1.0.0
             org.opencontainers.image.source=https://github.com/${{ github.repository }}
 
       - name: Create multi-arch manifest