Issue #3595533: vault page follow-up + Tugboat demo polish (#3595227)

Follow-up to MR !48 (merged) (#3595533), plus the demo-presentation tweaks from this session consolidated here (rather than a separate MR).

Vault page (#3595533)

• Mid-word wrapping: disable hyphens: auto on the vault table cells (Olivero broke short values like the scope column into "Lec-ture").
• Trust form title: the route _title was still "Add trusted consumer" (a YAML title missed by the code rename) and untranslated -- now "Add trusted service".
• Batch-button selection gate: a JS behavior disables each section's Delete/Decline/Stop-trusting button until a row is checked, so an accidental empty submit (reload, scroll-to-top, section recollapse) cannot happen. Progressive enhancement; server-side guard remains.

Tugboat demo (#3595227)

• Rename the demo-only module pdv_demo_lang -> pdv_demo (it now does switcher styling AND page-title typography; pdv_demo_language_switcher block id unchanged).
• Page-title hyphenation: demo CSS sets hyphens: manual on headings so long titles stop breaking mid-word ("confian-ce"). Demo-only -- not in the pdv module.

⚠️ TEMPORARY -- revert before merge

.tugboat/setup.php's French/demo gate is opened so this MR's child preview builds in French (for reviewing the title fix). Restore the base-only gate (=== 'branch') before merging.