i18n: build translated sentences in code so they read correctly in every language (TBv3 + Mapper) #2877

Summary

The pt-BR review of oclweb3#60 and oclmap#90 (#2866) found sentences that the UI builds by stitching translated fragments together, or by dropping raw English values into translated text. No catalog edit can make these read correctly in Portuguese (or Spanish). They need code changes so that each sentence is a single translatable string with interpolated values. This ticket holds the code-side fixes that were deliberately kept out of the translation PRs so those could merge.

Acceptance criteria

• DeleteEntityDialog, ReleaseVersion, ResourceReferences and repo.version.form.* take a translated resource-type label instead of the raw API type (Collection, concept, Source Version). The hardcoded 'versions, ' and 'concepts and mappings' in RepoHome go through i18n. Sentences avoid gendered articles before {{resourceType}}, or use per-type keys. (The unused common.object_types map added in oclweb3#60 can serve here; otherwise remove it.)
• Activity feed (Events.jsx, DashboardEvents.jsx): each event type × object type is a whole-sentence key with preposition and site name, e.g. "Entrou no OCL", "Entrou em uma Organização X". The no-object "Joined" event stops using the API's English description. Remove the unused event_types.updated and .source. Add event_types / event_object_types for es and zh.
• Error pages (Error401/403/404, ErrorUI): replace the please + link + or + … fragments with <Trans> sentences.
• Search placeholders (SearchInputDrawer): replace the fragment chains with <Trans> sentences.
• Relative times and dates follow the UI language: set the Moment locale at startup from the persisted language (both apps) and on change (oclweb3), and localize the M/D/YYYY formats in constants.js.
• <html lang> follows the selected language.
• oclweb3: guard UserMenu when the stored language isn't in LANGUAGES (a stored zh currently throws). Drop the i18n.languages = … overwrite in both apps.
• Hardcoded English found near the touched code: UserProfile.jsx "Joined {date}" and Mapper ProjectLogs.jsx "{user} at {date}".

Related: #2866, OpenConceptLab/oclweb3#60, OpenConceptLab/oclmap#90