Applies_to: Expand versioning features

[cotti]

This PR provides a set of adjustments to the inner workings of versioning in the context of applies_to. This draft will be further updated with front-end changes, but badge-related changes can be checked independently.

It is part of #2135.

Problem description

Describing versions within applicability contains several quirks and limitations, such as:

• Lack of version range support: Authors can only specify single versions, making it difficult to document features that span multiple versions
• Patch-level badge overload: Showing full Major.Minor.Patch versions creates visual clutter, specially for more complex applicability scenarios
• Missing base version context: When no version is specified for versioned products, readers don't know they're viewing version-specific documentation (e.g., "Stack 9.0+")

Proposed changes

Version Specification (VersionSpec)

A new VersionSpec class has been created. It builds on SemVersion, and supports the following versioning types:

• Greater than or equal to: x.x+ or x.x (default)
• Range (inclusive): x.x-y.y
• Exact version: =x.x

// Examples:
stack: ga 9.1          // 9.1+ (default behavior)
stack: ga 9.1+         // 9.1+ (explicit)
stack: preview 9.0-9.2 // Range
stack: beta =9.1       // Exact version only

Simplified Badge Display

• Badges now display Major.Minor versions only, regardless of patch specification:
  9.5.0, 9.5.1, 9.5.6 -> all display as 9.5 or 9.5+

Base Version Display

When no version is specified for versioned products, the base version is now shown:

Before: stack: ga -> Badge shows just "Stack"
After: stack: ga -> Badge shows "Stack│8.0+" (assuming base = 8.0)

Unversioned products continue to show no version.

Validation Rules

Implemented validation in ApplicableToYamlConverter:

• One version declaration per lifecycle
• Only one "greater than or equal" per entry is allowed
• Ranges must not have a minimum version larger than the maximum version
• Overlapping version ranges are not allowed

# Valid:
stack: ga 9.2+, beta 9.0-9.1
stack: ga 9.2, beta =9.1

# Invalid - throws a warning:
stack: ga 9.2+, beta 9.0+     # Multiple >=
stack: ga 9.2+, beta 9.0-9.2  # Overlapping ranges

Tooltip -> Popover overhaul

The badge tooltip was replaced by a popover component.

[github-actions]

🔍 Preview links for changed docs

• docs/syntax/applies.md
• docs/testing/req.md

[reakaleek]

There are two test cases that made me curious.

Otherwise, LGTM.

Nice work.

[reakaleek]

➕ thanks for fixing this and making it properly.

[reakaleek]

I'm wondering a bit why there are so many warnings. What's the reason we can't do this backwards compatible?

[florent-leborgne]

LGTM functionally what's implemented here works as expected.

• Some corner cases (that are more about handling contribution mistakes or very rare scenarios) might still require fixing or better validation handling
• This PR doesn't seem to implement the x.x.x! syntax to force showing patches - this is fine for me as I don't think we need it

It'd be nice to get this merged soon so we can do a cleanup pass with the cumulative docs group on the content, so that we can re-enable warnings asap.