fix(chore): no leading number in less variables

[lubber-de]

Description

Since LESS 4.8.0, variables with leading numbers are deprecated and support will be removed by LESS 5.0

This PR:

• renames all @12px variables to @absolute12px
• adds a leading "x" to flag map keys (their unicode starts with "1")
• adjust flag generator to understand the logic

BREAKING CHANGE, as custom themes using any of those variables will break the build

Closes

#3577

Summary by CodeRabbit

• Bug Fixes

  • Corrected flag asset URL generation for country, class, and alias selectors.
  • Standardized flag identifiers to ensure generated flag images load correctly.

• Style

  • Updated theme spacing, sizing, border-radius, and positioning values to use consistent absolute-pixel tokens across Bootstrap, default, and GitHub themes.
  • Preserved existing visual dimensions while improving consistency in generated styles.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: c014c2c7-7e4a-4510-9fb7-c8578233d29d

📥 Commits

Reviewing files that changed from the base of the PR and between de88af3 and 661aa3d.

📒 Files selected for processing (18)

• src/definitions/elements/flag.less
• src/themes/bootstrap3/elements/button.variables
• src/themes/default/collections/breadcrumb.variables
• src/themes/default/collections/form.variables
• src/themes/default/collections/menu.variables
• src/themes/default/elements/flag.variables
• src/themes/default/elements/header.variables
• src/themes/default/elements/label.variables
• src/themes/default/elements/loader.variables
• src/themes/default/elements/placeholder.variables
• src/themes/default/elements/segment.variables
• src/themes/default/globals/site.variables
• src/themes/default/modules/checkbox.variables
• src/themes/default/modules/dropdown.variables
• src/themes/default/modules/popup.variables
• src/themes/default/views/feed.variables
• src/themes/github/elements/header.variables
• src/themes/github/elements/input.overrides

Included review availability: Your plan provides up to 8 included reviews per hour; 7 remain after this review.

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📝 Walkthrough

Walkthrough

The PR renames exact-pixel theme variables, updates related references across themes, and normalizes flag Unicode keys for generated background-image URLs.

Changes

Theme tokens and flag assets

Layer / File(s)	Summary
Rename exact-pixel tokens src/themes/default/globals/site.variables	Exact-pixel variables now use the @absolute*px names. Rem conversion formulas remain unchanged.
Migrate theme variable references src/themes/bootstrap3/..., src/themes/default/..., src/themes/github/...	Component and collection variables now reference the renamed absolute-pixel tokens.
Normalize flag asset keys src/definitions/elements/flag.less, src/themes/default/elements/flag.variables	Flag keys gain an x prefix. Flag generation removes the prefix before constructing background-image URLs.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: ⚪ Minimal · up to 661aa

The change renames deprecated LESS variables and updates flag generation; no actionable current-head correctness or merge-blocking risk remains, so it is merge-ready after normal checks.

Suggested reviewers: ko2in, colinfrick, prudho, y0hami

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title describes the LESS variable rename and reflects a real part of the changes, but it does not mention the flag key updates.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0 files. (18 skipped: 18 unsupported.)
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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