Extract shared resource container infrastructure across generators and loaders

[frostney]

Summary

Extract the duplicated binary resource container code shared by the three generator scripts (JS) and three embedded resource loaders (Pascal) into shared modules.

Why

After #607 added the Unicode data generator and loader, three independent generators and three independent loaders now contain structurally identical code. The duplication is stable — the binary format is the same across all three — so extracting it reduces maintenance surface without coupling unrelated domains.

Current behavior

JS generators — generate-timezone-data.js, generate-intl-data.js, and generate-unicode-data.js each contain identical copies of:

• writeUInt32LE, buildResourceContainer, generateResourceFile
• pascalUnitNameForOutput, resourceFileForOutput
• Constants: RESOURCE_HEADER_SIZE, RESOURCE_ENTRY_SIZE, RESOURCE_FORMAT_VERSION, PASCAL_UNIT_IDENTIFIER_PATTERN, MAX_REDIRECTS, DOWNLOAD_TIMEOUT_MS

~150 lines duplicated per script.

Pascal loaders — Goccia.Temporal.TimeZoneData.pas, Goccia.Intl.CLDRData.pas, and Goccia.RegExp.UnicodeData.pas each contain structurally identical:

• HasExpectedMagic, TryReadEmbeddedHeader, TryReadEmbeddedEntry, TryGetEntryName / TryCompareEntryName, TryFindEmbeddedEntry, TryReadEmbeddedResource

Only the constant prefixes (UCD_ / TIME_ZONE_DATA_ / CLDR_DATA_) and magic bytes differ. ~150 lines duplicated per loader.

Expected behavior

JS: A shared scripts/lib/resource-container.js module exporting the container-building and resource-compilation functions. Each generator imports the shared module and only defines its domain-specific logic (data downloading, parsing, entry collection).

Pascal: EmbeddedResourceReader.pas (already exists with low-level primitives) extended with a generic container reader parameterized by magic bytes, or a new EmbeddedResourceContainer.pas shared unit providing TryReadHeader, TryFindEntry, and TryLoadFromResource. Each loader delegates to the shared unit and only defines its domain-specific extraction logic.

Scope notes

• The binary format (8-byte magic, 6×uint32 header, 16-byte entry table, names section, data section) is already unified across all three resources — this is a pure deduplication, not a format change.
• EmbeddedResourceReader.pas already provides HasBytesAvailable, ReadUInt32LE, and CopyStringFromBytes. The header/entry/search layer is the missing abstraction.
• The downloadFile function is also duplicated between the timezone and unicode generators but not the Intl generator (which uses npm). Only extract download if it can be shared cleanly.
• Related: Generate full Unicode property tables for regex \p{} escapes #607 (introduced the third copy).