Launcher Polish — Phase 5: Icon Rendering Primitive

[Emperiusm]

Task

Implement Phase 5 — Icon Rendering Primitive from the launcher UI polish plan.

Plan Reference

docs/superpowers/plans/2026-04-03-launcher-ui-polish.md

Read the plan's Phase 5 section. Phases 0–3 are already merged. Note: Phase 4 is deferred to Pass 3; Phase 5 comes next per execution order (Pass 2).

Tasks (9)

Task	Summary
TASK-021	Acquire icon font Already done — MaterialSymbolsOutlined.ttf is in assets/fonts/
TASK-021a	Icon font subset audit — verify all 28+ codepoints are present
TASK-022	Load icon font in TextRenderer as a secondary FontSystem family
TASK-023	Create Icon widget struct with new(), with_size(), with_color()
TASK-024	Implement Icon::paint() — emit a TextRun { icon: true, ... }
TASK-025	Define icon codepoint constants (ICON_HOME, ICON_SETTINGS, etc.)
TASK-025a	Add text_width_exact() helper in text_renderer.rs
TASK-025b	Add Dropdown.with_trailing_icon() builder in dropdown.rs

Constraints

• TASK-021a must pass before TASK-022 (font must have all codepoints before loading).
• After each task, run cargo check -p prism-client.
• After all tasks, run cargo test --workspace.
• Update the Progress Tracker: check off Phase 5.
• Single commit: feat(client): Phase 5 — icon rendering primitive
• Branch: launcher-polish/phase-5
• Do NOT modify files outside crates/prism-client/.

Labels

launcher-polish, phase-5, pass-2