fix(jspromise): convert panics to EngineError::Panic using js_expect

[KaustubhOG]

Part of #3241

Converts all 23 panics in jspromise.rs to EngineError::Panic using
js_expect introduced in #4828.

Patterns converted:

• .js_expect() on internal promise operations that cannot fail
• .js_expect().map_err(Into::into) for methods returning JsResult<JsPromise>

Signature changes:

• resolve(), reject(), from_result() → JsResult<Self>
• then(), catch(), finally() → JsResult<JsPromise>
• all(), all_settled(), any(), race() → JsResult<JsPromise>
• into_js_future() → JsResult<JsFuture>

Files modified: 6

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	52,963	52,963	0
Passed	49,666	49,666	0
Ignored	2,284	2,284	0
Failed	1,013	1,013	0
Panics	0	0	0
Conformance	93.77%	93.77%	0.00%

Tested main commit: faaf64d6af04ed7691edac6cae7dc9d1bc38a8f8
Tested PR commit: 68d6bf40209169d5f8cf6a6b71a2a5f48e9e1f16
Compare commits: faaf64d...68d6bf4

[codecov]

Codecov Report

❌ Patch coverage is 9.67742% with 28 lines in your changes missing coverage. Please review.
✅ Project coverage is 57.13%. Comparing base (6ddc2b4) to head (68d6bf4).
⚠️ Report is 756 commits behind head on main.

Files with missing lines	Patch %	Lines
core/engine/src/object/builtins/jspromise.rs	10.34%	26 Missing ⚠️
core/engine/src/builtins/array/from_async.rs	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4875      +/-   ##
==========================================
+ Coverage   47.24%   57.13%   +9.88%     
==========================================
  Files         476      555      +79     
  Lines       46892    60600   +13708     
==========================================
+ Hits        22154    34623   +12469     
- Misses      24738    25977    +1239     

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[Razican]

Great work! Thanks! :)