fix: svelte dispose functionality

[signalize]

resolves #1566

• This change fixed the error
• Updated the docs
• With this change it's possible to do this:

let value = $derived(Posts.find().fetch());

instead of

let items = $state.raw([]);
$effect(() => {
  const cursor = Posts.find({});
  items = cursor.fetch();

  return () => {
    cursor.cleanup();
  };
});

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (fc98b66) to head (88f6e48).
Report is 2 commits behind head on main.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #1595   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           56        56           
  Lines         1789      1796    +7     
  Branches       417       418    +1     
=========================================
+ Hits          1789      1796    +7     

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[codecov]

Bundle Report

Changes will increase total bundle size by 326 bytes (0.0%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
@signaldb/svelte	1.01kB	326 bytes (47.45%) ⬆️

Affected Assets, Files, and Routes:

view changes for bundle: @signaldb/core

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
index.cjs29.js	539 bytes	815 bytes	195.29% ⚠️
index29.mjs	539 bytes	808 bytes	200.37% ⚠️
index.cjs27.js	-52 bytes	763 bytes	-6.38%
index27.mjs	-52 bytes	756 bytes	-6.44%
index.cjs28.js	-487 bytes	276 bytes	-63.83%
index28.mjs	-487 bytes	269 bytes	-64.42%

view changes for bundle: @signaldb/svelte

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
index.svelte.js	286 bytes	805 bytes	55.11% ⚠️
index.svelte.d.ts	40 bytes	208 bytes	23.81% ⚠️