finance: skills document slash commands the plugin doesn't ship (/je, /sox, /flux), and two skill pairs overlap #1283

The finance plugin has a skills/ folder but no commands/, yet several skills tell the user to run slash commands:

• finance/skills/journal-entry/SKILL.md, line 18: /je <type> <period>
• finance/skills/sox-testing/SKILL.md, line 18: /sox <control-area> <period>
• finance/skills/financial-statements/SKILL.md, line 175: "Offer to drill into any specific variance with /flux"

None of these commands exist, so the model offers the user something that fails. Suggested fix: refer to the skills by name (for example /finance:journal-entry), or add the commands.

Also, two pairs of skills have near-identical descriptions and compete for the same requests: journal-entry / journal-entry-prep, and sox-testing / audit-support. Merging each pair, or making their descriptions say when to use one rather than the other, would make triggering predictable.