Add Firmware Config web shortcut and build concurrency

[Tareku99]

Summary

• Add a standalone overlay that serves /firmware-config-shortcut.js.
• Inject a small floating Firmware Config shortcut into Fluidd and Mainsail during firmware build.
• Link the shortcut to /firmware-config/.
• Collapse the shortcut to a compact tab after a short delay, then expand on pointer hover or keyboard focus.
• Add workflow concurrency so newer pushes cancel older in-progress builds for the same workflow/ref.

Scope

This PR is focused on issue #570 and the build workflow concurrency helper.

It does not include Anycubic ACE, RFID, or other experimental integration changes.

Visual example of what this looks like

Checks

• git diff --check
• bash -n overlays/firmware-extended/69-app-firmware-config-shortcut/scripts/01-inject-shortcut.sh

Closes #570

[github-actions]

✅ Build Artifacts

Version: 1.5.1-paxx12-test-pr-571
Build: 04fe2b9 (merge of aed788f into develop)
Duration: 3m 51s

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extended-build	254.38 MB

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[github-actions]

✅ Build Artifacts

Version: 1.5.1-paxx12-test-pr-571
Build: 9db0985 (merge of 30821cb into develop)
Duration: 3m 16s

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extended-build	254.38 MB

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[github-actions]

✅ Build Artifacts

Version: 1.5.1-paxx12-test-pr-571
Build: b5d1118 (merge of 5e6b352 into develop)
Duration: 3m 2s

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extended-build	254.38 MB

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[github-actions]

✅ Build Artifacts

Version: 1.5.1-paxx12-test-pr-571
Build: ae67e38 (merge of 24546cc into develop)
Duration: 2m 54s

Artifact	Size
extended-build	254.38 MB

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[github-actions]

✅ Build Artifacts

Version: 1.5.1-paxx12-test-pr-571
Build: f84c629 (merge of 72c1490 into develop)
Duration: 2m 49s

Artifact	Size
extended-build	254.38 MB

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[github-actions]

✅ Build Artifacts

Version: 1.5.1-paxx12-test-pr-571
Build: dbb3e56 (merge of 7e4ae4b into develop)
Duration: 3m 8s

Artifact	Size
extended-build	254.38 MB

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[github-actions]

✅ Build Artifacts

Version: 1.5.1-paxx12-test-pr-571
Build: 0be0ca2 (merge of 9e6fe4e into develop)
Duration: 3m 4s

Artifact	Size
extended-build	254.38 MB

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[Tareku99]

Been using this build and everything is working fine, not sure what all the requirements are to make the cut in the next release. This is not a new feature, just a UX improvement imo.
I tried to make it as non-intrusive and no maintenance as possible.

Edit: please let me know about the workflow concurrency change, from personal experience, it is a nice edit to have when many people are pushing fast changes to a branch. Saves on time and money :)

[github-actions]

✅ Build Artifacts

Version: 1.5.1-paxx12-test-pr-571
Build: 9470811 (merge of e16a06f into develop)
Duration: 2m 53s

Artifact	Size
extended-build	215.33 MB

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[Tareku99]

Pulled in develop after the recent commits, tested again and all is working well.
@paxx12 Ready for review

[Tareku99]

Are we interested in this as well for the upcoming 1.5.3 release that is being bundled or should we close it without merging?