fix: normalize AD_Language in preferences and add typed PreferenceUtil getters

[EdwinBetanc0urt]

Summary

• MPreference.beforeSave now normalizes the Language attribute to a valid AD_Language code at storage time, regardless of which caller wrote the row.
• A new public MPreference.normalizeLanguageCode(String) exposes a tiered lookup (2-char ISO → LanguageISO, full code → AD_Language, anything else → Name/PrintName) as the single source of truth for resolving any language string into a canonical code.
• PreferenceUtil gains typed, validated getters (getLanguagePreference, getRolePreference, getClientPreference, getOrganizationPreference, getWarehousePreference) and delegates its internal normalization to MPreference.normalizeLanguageCode, eliminating the duplicated SQL.
• PreferenceUtil.saveSessionPreferences skips the language write when the supplied value does not normalize, so a junk caller cannot overwrite a previously good row.

Root cause

Legacy UI flows (most visibly the ZK UI login/role flow) persisted the localized display name returned by Language.getName() — e.g. "Español (MX)" — into AD_Preference.Value for the Language attribute. Downstream consumers that read the preference as an identifier (gRPC session-info, the Vue/Tepuy menu API, Elasticsearch index resolution, print engines) then forwarded that value as a query parameter, breaking with HTTP 500 when no index/locale could be resolved from a display name. With multiple callers writing to AD_Preference across the platform, a single point of normalization at the model layer is needed so the data shape is invariant to the writer.

Changes

org/compiere/model/MPreference.java

• New constant ATTRIBUTE_LANGUAGE = "Language" used by beforeSave.
• beforeSave now invokes the new normalizeLanguageCode for rows whose Attribute is Language, replacing the stored value with the canonical AD_Language code when a match is found. When no row matches, the raw value is left in place so existing data is not destroyed.
• New public static String normalizeLanguageCode(String input) — tiered SQL lookup against AD_Language, returns null when the input does not resolve.
• New imports: org.compiere.util.DB, org.compiere.util.Util.

org/spin/service/grpc/util/base/PreferenceUtil.java

• New getPreferenceValue(int userId, String attributeName) — fetches the most recent value of one preference for a user.
• New parseIdOrNegative(String value) — parses an AD_*_ID from preference text, returning -1 for missing/non-numeric values so callers can fall back to a system default and never trust unparseable data.
• New typed getters: getLanguagePreference, getRolePreference, getClientPreference, getOrganizationPreference, getWarehousePreference. These collapse the previous loop-and-switch retrieval pattern at call sites and document the validation expectations (role/org callers MUST re-check access — privilege-escalation defense).
• saveSessionPreferences: for the Language row, the new value is normalized via the shared MPreference helper before being written; when normalization returns null (the caller passed a display name or unknown string) the iteration continues, leaving the existing row untouched.
• Internal normalizeLanguageCode is reduced to a thin wrapper that delegates to MPreference.normalizeLanguageCode, so the SQL lives in one place.
• Removed unused org.compiere.util.DB import.

Compatibility

• Existing rows in AD_Preference are not migrated. They auto-heal on the next save() cycle thanks to MPreference.beforeSave, and the read path (PreferenceUtil.getLanguagePreference) tolerates the legacy display-name format during the transition.
• No public API was removed. getSessionPreferences and saveSessionPreferences keep their existing signatures; the new typed getters are additive.
• No DDL changes; the new SQL is read-only and uses ROWNUM = 1 for cross-DB compatibility.

Test plan

• On a database where AD_Preference contains rows with a display-name value for Attribute = 'Language' (e.g. Español (MX)), trigger any update of that row (role switch, login flow that saves preferences) and verify the value is rewritten to the matching AD_Language code (es_MX).
• Insert a fresh AD_Preference row programmatically with the language attribute set to a 2-char ISO (es), save, and confirm Value is stored as the canonical AD_Language code.
• Insert with an unknown string (e.g. xyz), save, and confirm the value is left in place (no exception, no overwrite to null).
• Call PreferenceUtil.getLanguagePreference on a row known to hold a legacy display name and confirm it returns the canonical code.
• Call PreferenceUtil.saveSessionPreferences with language = "Español (MX)" for a user who already has a valid stored language; confirm the stored value is NOT overwritten (skip-on-junk guarantee).
• Build downstream services that consume adempiere-core (e.g. the gRPC server and report-engine) against this version and confirm no compilation regressions.