feat: add release dates and descriptions to collections

[TowyTowy]

Closes #196.

Adds two fields to every entry in collections.json:

• release_date — ISO 8601 (YYYY-MM-DD), curated in utils/collectionReleaseDates.json keyed by collection id (same pattern as utils/specialNotes.json).
• description — the official set_description game string via $t(), or null when Valve provides none.

Why curated: release dates aren't present in items_game/csgo_english (as noted in the issue), so they're maintained in a JSON map. Where a collection is tied to a case, the value matches the case's first_sale_date already published in crates.json; a handful of 2013–2014 cases whose first_sale_date is a bulk market-enable artifact (the three Arms Deal sets all read 2013-09-20, the three eSports sets all read 2014-07-09) were corrected to their real release dates via patch notes; the rest are sourced from CS wiki / patch notes.

Descriptions are only shipped when Valve supplies an official string (currently 8 collections, e.g. the Bravo/Alpha grant collections and the charm/sticker capsules) and auto-populate as more are localized — no hand-written text.

Acceptance contract

• Default: both fields present on all collections; null where unknown. Purely additive — no existing field changed (regen diff is +212/-0 for en).
• Backwards-compatible: consumers ignoring the new keys are unaffected.
• Out of scope (deliberate): hand-writing non-official descriptions for the ~98 collections with no official string, and dating the XP-shop "Limited Edition Item" (null — no reliable public date).

Lower-confidence dates, flagged for review: 2018 Nuke/Inferno (2018-09-01, approximated to the FACEIT London major window), Cache (2014-08-08), Bank (2013-11-27), Genesis (2025-09-17), Dead Hand (2026-03-12 vs SteamDB's "11 March 2026"), and the Oct 2025 sticker/charm sets (2025-10-01, though the in-game description text says "September 2025"). Happy to adjust any of these.

Data files are left for the update bot to regenerate across all languages.

[samplics]

Bad PR, not really evidence based

[TowyTowy]

Happy to correct any entry that's wrong — which dates do you see as not evidence based? The sourcing is described in the PR body: the 38 case-linked collections reuse the first_sale_date values this repo already publishes in crates.json, six 2013–2014 cases are corrected against patch notes because their first_sale_date is a bulk market-enable artifact (the three Arms Deal sets all read 2013-09-20, which is provably not their release), and the map/operation collections are anchored to documented update dates. The six I'm least confident about are explicitly flagged in the PR description. If you have a better source for any specific collection I'll gladly update the map.