Sync to latest ITensorPkgSkeleton template

[mtfishman]

Summary

Sync the repo to the latest ITensorPkgSkeleton template. Most workflow files now match the template verbatim; IntegrationTest.yml keeps the existing downstream packages (ITensorBase, UnallocatedArrays).

Notable behavioral changes:

• Pre-commit hook switches from runic-pre-commit to itensorformatter-pre-commit v1.0.0 (this is what supersedes [pre-commit.ci] pre-commit autoupdate #27, which autoupdated the now-retired runic hook).
• Tests.yml and IntegrationTest.yml gain status-gate jobs (tests-gate, integration-gate) so branch protection works correctly when matrix legs are skipped.
• IntegrationTest.yml moves to pull_request_target with secrets: inherit, drops the Project.toml paths filter, and adds fail-fast: false.
• Registrator.yml gains the issue_comment trigger plus issues: write permission, and uses secrets: inherit.
• CompatHelper.yml uses secrets: inherit.
• Tests.yml and IntegrationTest.yml trigger on converted_to_draft.
• LiterateCheck.yml is removed.
• test/runtests.jl delegates to ITensorPkgSkeleton.runtests; docs/make.jl uses ITensorFormatter.make_index! instead of an inlined Literate driver, and docs/make_index.jl / docs/make_readme.jl are removed.
• Root Project.toml gets a [workspace] section; test/Project.toml and docs/Project.toml get [sources.UnspecifiedTypes] entries pointing at ...
• Patch version bump 0.1.8 → 0.1.9.

Closes #27.

Test plan

• CI green on all workflows.
• test/runtests.jl passes locally (Aqua + basics).

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 26.92%. Comparing base (05f7420) to head (7337eeb).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #28   +/-   ##
=======================================
  Coverage   26.92%   26.92%           
=======================================
  Files           3        3           
  Lines          26       26           
=======================================
  Hits            7        7           
  Misses         19       19           

Flag	Coverage Δ
docs	0.00% <ø> (ø)

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