[1.1.0] Fix KeyError and add platform-aware downloads

[unurgunite]

Summary

Fixes KeyError: Missing hash key when using --upgrade-ide with JetBrains products not present in a hardcoded map (e.g. PhpStorm), and makes IDE downloads platform-aware (macOS / Linux / Windows instead of always .dmg).

Fixes #21.

Changes

• Utils.product_code — single case-insensitive {product=>code} mapping (PhpStorm->PS, IntelliJ->IU, Rider ->RD, etc.) with safe fallback. DetectProducts.infer_code and IDEUpdater now share it instead of two divergent maps.
• ide_updater.cr — --upgrade-ide:
  • no more Hash#[] KeyError crash on unknown/lowercase product names (phpstorm via --ide-path now resolves correctly);
  • download key chosen by OS + arch: mac/macM1, linux/linuxARM64, windows (previously always .dmg);
  • saved file extension follows the platform.
• main.cr — --list-ide-releases normalizes the product code too (phpstorm works).
• CI — pin Crystal to 1.17.1 (matching .tool-versions); ameba 1.6.4 doesn't build under Crystal 1.21 (preview_mt removed, Lexer#next_string_array_token gone).
• shard.lock — uing 0.1.1 -> 0.1.2.
• Specs — Utils.product_code coverage (mapping, lowercase, fallback).

Verification

• crystal spec — 94 examples, 0 failures
• bin/ameba — 26 files inspected, 0 failures
• Manual: --product PhpStorm --upgrade-ide fetches PS (no KeyError)
• Manual: --ide-path /Applications/phpstorm --upgrade-ide -> PHPS... -> PS