refactor(renderer): route all Phosphor icon imports through ui/icons barrel

Create src/renderer/components/ui/icons.ts as the single re-export point
for every Phosphor icon the renderer touches, then rewrite the 95 files
that previously imported directly from "@phosphor-icons/react" to pull
from the relative-path-to-barrel instead. The TitleBar commit earlier
in this series already used ui/icons; this commit extends the pattern
to the rest of the renderer.

Benefits now wired in:
  - one location where bundle tree-shaking can be reasoned about,
  - typos like Briefcase vs BriefCase show up against a finite list,
  - re-theming or swapping icon sets is a one-file edit,
  - a lint rule that flags raw @phosphor-icons/react imports can be
    added later without mass-rewriting call sites.

The barrel also re-exports the `Icon` type so call sites that type
icon props against the Phosphor component type work unchanged.

Test count stays at 363 passing; typecheck stays at 156 errors.

src/renderer/components/execution/TaskCreator.tsx

@@ -1,6 +1,6 @@
 import { useState } from "react"
 import { AnimatePresence, motion } from "framer-motion"
-import { ListChecks } from "@phosphor-icons/react"
+import { ListChecks } from "../ui/icons"
 import type { GoalRecord, ProfileSnapshot, ProjectRecord, WorkspaceRecord, TaskRecord } from "@shared/types"
 import { useT } from "../../i18n"
 import { unwrap } from "../../lib/desktop"