Add Italian localization for BGEE/SoD/BG2EE Core Fixes

[Sauler89]

Summary

This PR adds an Italian localization for the EE Fixpack Core Fixes covering BGEE, Siege of Dragonspear, and BG2EE, and enables Italian in the WeiDU language selector.

The translation was rebuilt against the current English files on master and checked against the official Italian BGEE/SoD and BG2EE dialog.tlk/dialogf.tlk files, using the terminology and style of the official Italian localization (Gli Allegri Buffoni) as the primary reference.

Included

• installer strings (weidu.tra)
• BGEE helper strings (bgee.tra)
• BG2EE helper strings (bg2ee.tra)
• BGEE Core string fixes: 26 entries
• SoD Core string fixes: 4 entries
• BG2EE Core string fixes: 51 entries
• matching fixes_*.tph mappings
• updated copy_from_iwdee.tra
• copy_from_sod.tra regenerated from the official Italian SoD TLK donor strings
• updated luke/polymorph_overhaul.tra
• Italian luke/shared.tra
• Italian language entry in setup-eefixpack.tp2
• minimal iwdee.tra / pstee.tra compatibility stubs so the globally registered Italian language can be selected safely on those games while untranslated Core strings continue to fall back to English

Existing Italian files

The repository already contained a partial it_it directory. This PR completes the BGEE/SoD/BG2EE Core localization and also updates stale/incomplete files there.

In particular:

• copy_from_iwdee.tra is synchronized with the current Nishruu donor text and mechanics.
• luke/polymorph_overhaul.tra had a key mismatch: the old Italian @2 translated “Devour brain”, while current English @2 is the Water Elemental shapeshift description and @3 is “Devour brain”. This PR realigns the keys and adds the missing entry.

Validation

• all .tra keys checked for uniqueness and expected coverage
• placeholders such as <PRO_HIMHER>, <PRO_HISHER>, and <PRO_MANWOMAN> preserved
• regex escapes and sound references preserved
• BG2EE male/female journal variant at strref 7148 preserved
• copy_from_sod.tra: all 27 donor strings checked against the official Italian TLK
• installer language patch dry-run tested successfully
• archive/file integrity and UTF-8 text checked

Maintainer note

fixes_bg2ee.tra includes Italian strings for @25209 and @45867 because those entries are present in the current English TRA. The Italian fixes_bg2ee.tph intentionally mirrors the current English TPH and therefore does not map those two entries.

Scope / GTU

This PR intentionally does not add an Italian Game Text Update. GTU changes are language-specific editorial corrections and should be audited independently against the Italian TLKs rather than translated mechanically from English.

The Core localization in this PR covers BGEE/SoD/BG2EE. IWDEE/PsTEE Core strings are not claimed as complete here; the two compatibility TRA files only allow the globally registered Italian language to load safely and preserve the existing English fallback until authoritative Italian Core translations are added separately.