fix(links): let CivitAI and HuggingFace links coexist (#1094)

A model could have CivitAI metadata and a HuggingFace link at the same time,
but only one of the two "View on ..." entries ever rendered, because both the
model modal and the card globe asked the `from_civitai` provenance flag which
source to show. `set_hf_url` wrote `false` and a CivitAI refresh wrote `true`,
so whichever ran last erased the other: linking HF hid "View on CivitAI" even
though the civitai payload was still in the sidecar, and (on the card) a later
refresh pointed the single globe icon back at CivitAI, hiding the HF entry.

Decide the links from the data itself instead:

- `set_hf_url` no longer touches `from_civitai`; it records where the metadata
  came from, and HF provenance is already tracked by `hf_url`.
- Add `hasCivitaiSource(civitai)` in the shared card/modal utils and gate the
  modal's CivitAI link, the card globe (title, enabled state, click target,
  new `data-has_civitai`) and the context-menu `civitai` action on actual
  CivitAI data (`modelId` / `model_id` / `id`). A dual-source model now shows
  both links, and a CivitAI-only model with no `hf_url` stays as before.
- Agent HF enrichment (`PostProcessor.is_hf_model`) keyed off
  `not from_civitai`, which stopped being a synonym for "has an HF source" once
  both sources can coexist (and already broke after a CivitAI refresh flipped
  the flag back to true). Key it off `hf_url` directly; the post-processor
  tests move to that discriminator and gain a dual-source case.

Regression tests: the set-hf-url handler preserves civitai + `from_civitai`
and no longer forces the flag false, the modal renders both links (including
with `from_civitai: false`), and the card globe targets/opens the right source
and is disabled when neither is available.

Backend: 2749 passed. Frontend: 1098 JS + 91 Vue tests passed.

static/js/components/ContextMenu/ModelContextMenuMixin.js

@@ -446,7 +446,10 @@ export const ModelContextMenuMixin = {
                 this.downloadExampleImages(true);
                 return true;
             case 'civitai':
-                if (this.currentCard.dataset.from_civitai === 'true') {
+                // Gate on actual CivitAI data (not the `from_civitai` flag) so
+                // that linking HuggingFace does not make the model look like it
+                // has no CivitAI info (#1094).
+                if (this.currentCard.dataset.has_civitai === 'true') {
                     if (this.currentCard.querySelector('.fa-globe')) {
                         this.currentCard.querySelector('.fa-globe').click();
                     } else {