feat(myopencre): add initial MyOpenCRE page and CSV template download

[PRAteek-singHWY]

Summary

This PR introduces the first step of the MyOpenCRE frontend as described in issue #584 .

It adds a dedicated MyOpenCRE page that allows users to download a CSV mapping template (header-only), enabling them to map their own security standards (e.g. SOC2) to OpenCRE Common Requirements without using curl or CLI tooling.

What’s included

• New MyOpenCRE frontend page (React + TypeScript)
• Route and navigation entry for /myopencre
• Downloadable CSV mapping template (header-only) defining the expected column structure:
  • standard_name
  • standard_section
  • cre_id
  • notes
• No backend changes

What’s intentionally out of scope

• CSV upload functionality
• Feature flag handling (local vs Heroku)
• Import notifications

These will be handled in follow-up incremental PRs to keep the review surface small.

Related issue

Closes part of #584

Screenshots

• MyOpenCRE navigation entry

• MyOpenCRE landing page]

• Downloaded CSV mapping template

[PRAteek-singHWY]

Hi! I’ve squashed and re-signed the commits so everything is now verified.
Please let me know if any changes are needed. Thanks!

[PRAteek-singHWY]

This PR is part of the MyOpenCRE frontend flow resolving #584. Full context and next steps are summarized on the issue.

[northdpole]

this is amazing, thank you for working on this.
Can you please resolve the conflicts?
This is ready to go otherwise!

[PRAteek-singHWY]

this is amazing, thank you for working on this. Can you please resolve the conflicts? This is ready to go otherwise!

@northdpole Thanks sir, glad to hear that!
I’ll resolve the conflicts shortly.

[PRAteek-singHWY]

Thank you so much! @northdpole ✨
Conflicts are resolved and the branch is now up to date.
Please let me know if you’d like any changes or follow-ups.

[PRAteek-singHWY]

Fixed a shared header utility (.sr-only) in the base MyOpenCRE branch that was affecting hamburger alignment in stacked PRs.
Rebased dependent branches so the fix propagates cleanly.
Thanks again for the review .