fix: prioritize special package handlers over meta.source fallback in getPath()

[JorisHeadease]

Bug

SpecMapManager.getPath() uses meta.source (passed as the def parameter) as a web hyperlink for resources from dependency packages before the special package type handlers (Simplifier, VSAC, DICOM, etc.) are reached.

meta.source is a provenance URI per the FHIR spec — not a navigable web URL. The special package handlers exist specifically to generate correct links for their respective package types, but are never invoked when meta.source is non-null.

Call sites passing meta.source as def

Call site	File	Line
getResourcePath()	PublisherLoader.java	77
getIgPath()	PublisherLoader.java	97
getCorePath()	LoaderUtils.java	30, 34

All pass resource.getMeta().getSource() as the def parameter.

Fallback order before this fix

1. paths map (spec.internals)  → return if found
2. getSpecialPath()            → return if match
3. def (meta.source) != null   → return def          ← SHORT-CIRCUITS EVERYTHING BELOW
4. special package handlers    → Simplifier/VSAC/DICOM/PhinVads (never reached)
5. URI regex fallback
6. return null

Fallback order after this fix

1. paths map (spec.internals)  → return if found
2. getSpecialPath()            → return if match
3. special package handlers    → Simplifier/VSAC/DICOM/PhinVads (now reached)
4. def (meta.source) != null   → last-resort fallback
5. URI regex fallback
6. return null

Impact

For Simplifier-published packages (e.g. nictiz.fhir.nl.r4.zib2020) that lack spec.internals and have meta.source set, this produces broken hyperlinks in the generated IG HTML.

Before: Link points to http://decor.nictiz.nl/fhir/4.0/zib2020bbr- (truncated meta.source provenance URI)

After: Link points to https://simplifier.net/resolve?scope=nictiz.fhir.nl.r4.zib2020@0.12.0-beta.4&canonical=... (correct Simplifier redirect)

A reproduction project is attached to #1275.

Fixes #1275