Update Eldritch documentation for built-ins and stdlib

[KCarretto]

Identified missing and incorrect documentation for Eldritch functions by inspecting the source code in implants/lib/eldritch. Added a new section for built-in functions and updated the standard library documentation to match the current implementation. Regenerated the JSON documentation file used by the ShellV2 UI.

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PR created automatically by Jules for task 6686632203357497327 started by @KCarretto

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[github-actions]

Summary

Tests 📝	Passed ✅	Failed ❌	Skipped ⏭️	Other ❓	Flaky 🍂	Duration ⏱️
2690    ±0	2690    ±0	0    ±0	0    ±0	0    ±0	0    ±0	1ms    ±0

Previous Results

Build 🏗️	Result 🧪	Tests 📝	Passed ✅	Failed ❌	Skipped ⏭️	Other ❓	Flaky 🍂	Duration ⏱️
#1316	✅	2690	2690	0	0	0	0	43.4s

Insights

Average Tests per Run	Total Flaky Tests	Total Failed	Slowest Test (p95)
2690	0	0	6.0s

Slowest Tests

Test 📝	Results 📊	Duration (avg) ⏱️	Duration (p95) ⏱️
TestDockerExecutor_Build_ContextCancellation	1	6.0s	6.0s
eldritch-libsys: std::dll_inject_impl::tests::test_dll_inject_simple	1	5.1s	5.1s
TestInteractiveShell	1	5.0s	5.0s
TestOtherStreamOutput	1	5.0s	5.0s
imix::bin/imix: install::tests::test_install_execution	3	1.6s	4.6s
imix::bin/imix: install::tests::test_install_execution	3	1.6s	4.6s
imix::bin/imix: install::tests::test_install_execution	3	1.6s	4.6s
imix::bin/imix: tests::task_tests::test_task_streaming_output	3	3.0s	3.0s
imix::bin/imix: tests::task_tests::test_task_streaming_output	3	3.0s	3.0s
imix::bin/imix: tests::task_tests::test_task_streaming_output	3	3.0s	3.0s

_{🎉 No failed tests in this run. | 🍂 No flaky tests in this run.}

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