fix(mods): accept numeric Fantome versions

[NoName-txt]

What and why

Fantome metadata expects Version to be a string, but some existing mods use a numeric value such as "Version": 1.1.

This caused LTK Manager to reject the archive with:

Failed to parse info.json: invalid type: floating point 1.1, expected a string

A example is Sausage dog Naafiri, which could not be installed through the Install with LTK Manager flow.

This change:

• Accepts numeric and unquoted dotted Fantome version values.
• Converts those values to the string format expected by ltk_fantome.
• Uses the same parser for archive installation, cslol migration, and workshop peek/import flows.
• Preserves the original parse error for unrelated invalid metadata.

How it was tested

• Added a regression test using the failing "Version": 1.1 format.
• Added coverage for integer versions such as "Version": 2.
• Verified the RuneForge mod can proceed through the LTK Manager download/install flow.
• cargo fmt --all -- --check
• cargo clippy -- -D warnings
• cargo test - 449 tests passed across 3 suites.

Checklist

• Title follows Conventional Commits (feat: / fix: / docs: / chore:; ! for breaking)
• cargo fmt --all -- --check passes
• cargo clippy -- -D warnings passes
• cargo test passes
• README / docs update not required; no public API or documented workflow changed
• Tests added for the bug fixed or feature added