Fix parsing of last {...} section in *.items files to allow inner curly braces inside quoted values

[mannemiethe]

Hey Max, would be nice if you merge this:

Problem
*.items files were getting corrupted when the final {...} block contained nested curly braces in quotes (e.g., JSON-like metadata). The previous regex patterns assumed no additional braces inside this block, causing parsing errors and invalid file output.

Cause
The old regex for the last {...} section was too restrictive:

const REGEX_ITEM_CHANNEL_START = /\{\s*(\w*\s?=\s?"(?:[^"\\]|\\.)*"?,?\s*)+\}?/;
const REGEX_ITEM_CHANNEL_END = /.*[\},]/;
const REGEX_ITEM_CHANNEL_SECTION = /(\w+\=\"(?:[^"\\]|\\.)*\"\s*(\[.*?\])?)+/g;

These patterns failed when braces appeared inside quoted strings.

Solution
Replaced the regex with more permissive patterns that:
Capture the entire trailing {...} block.
Allow curly braces only inside quoted values (unquoted braces remain invalid).
Preserve optional [tags] syntax.

const REGEX_ITEM_CHANNEL_START = /\{.*\}$/;
const REGEX_ITEM_CHANNEL_END = /.*\}$/;
const REGEX_ITEM_CHANNEL_SECTION = /\w+="[^"]*"(\s*\[[^\]]*\])?/g;

Example (now supported):
String ColorLightOffice_name "Color Light Office" <colorlight> (ColorLightOffice) ["Control"] { initializeDefaultState="{'de_name': 'Farb Licht', 'en_name': 'Color Light', 'location2': {'name': 'Color Light', 'location': 'Office'}}" }

Impact:

✅ Fixes corruption when inner braces appear inside quoted values.
✅ Maintains compatibility with existing item definitions.
⚠️ Inner braces outside quotes remain invalid (by design).