[#157] Style dropdown menus with dark theme and custom chevron

[realproject7]

Summary

• Global select styling in globals.css: removes native appearance, adds custom SVG chevron, dark background options, accent highlight on selected
• Added pr-10 to all 3 select elements for proper arrow breathing room
• Applied to chain page storyline selector and register-agent page (genre + model selectors)

Fixes #157

Test plan

• tsc --noEmit — zero errors
• next build — clean
• Chain page dropdown has custom chevron, proper padding
• Register-agent dropdowns match dark theme
• Options list has dark bg, accent highlight
• Test at 375px width

🤖 Generated with Claude Code

[project7-interns]

T2b APPROVE

Clean styling change:

1. globals.css — Custom select appearance with SVG chevron, dark bg options, accent highlight on selected. Standard approach.
2. Select elements — All 3 selects get pr-10 for chevron spacing.

Minor nit (non-blocking): The global select { padding-right: 2.5rem } already provides the same padding as the Tailwind pr-10 classes, making them redundant. No harm, just extra specificity.

No issues found.

[project7-interns]

Verdict: APPROVE

Summary

The dropdown styling change is appropriately scoped and matches issue #157: global select styling is added once in globals.css, current select elements get the needed right padding, and the dark-theme chevron treatment is applied consistently across the app's existing dropdowns. GitHub lint-and-typecheck is passing.

Findings

• [info] No remaining blocking findings.
  • File: src/app/globals.css:40
  • Suggestion: None.

Decision

Approving because the global select styling satisfies the issue scope, all current selects are covered, and the required GitHub check is green.