build(deps-dev): bump vite to 8 and typescript to 6 in /ui (#140)

## What broke and how it was fixed

**vite 6.0.0 -> 8.1.5** (`ui/package.json`). Build/lint/tests all pass
unchanged with the existing `vitest` 2.1.9 + `@vitejs/plugin-vue` 6.0.8
(both already declare vite 8 in their peer ranges - no peer-dep
incompatibility, contrary to my first guess). The only fallout was a
~0.4pp UI coverage dip: vite 8's different bundling/sourcemap output
shifts which branches land as "uncovered" in a few components
(`AccountList.vue`, `SourceTable.vue`, `Activity.vue`). Closed the gap -
and then some - by adding `src/__tests__/app-shell.test.ts`, a smoke
test for `App.vue` (the app shell), which had **zero** mount coverage
before this (0% -> 98.5% on that file alone). Net UI line coverage:
**88.58% -> 89.36%** locally (CI's cached `main` baseline is 88.51%).

`vitest` 4.1.x is the first line that officially declares vite-8
support, and I tried it - but it switches `@vitest/coverage-v8` to
AST-aware remapping, which reports substantially *lower* (~84%) coverage
on this codebase. That's not a real regression in test quality, just a
stricter/more-accurate measurement, but it can't clear the CI
coverage-regression gate without a baseline reset (which I can't do
without merging). So the vitest bump is **deliberately deferred** - left
a comment in `vitest.config.ts` explaining why, so it isn't "helpfully"
redone later and silently breaks the gate.

**typescript 5.6.0 -> 6.0.3** (`ui/package.json`). The only break was
`tsconfig.json`'s `baseUrl`, deprecated in TS 6 (`TS5101`, removed in TS
7). Removed it and converted the `"@/*"` path mapping to the explicit
relative form (`"./src/*"`) - TypeScript resolves `paths` relative to
the tsconfig file when there's no `baseUrl`, so behavior is unchanged.
`vue-tsc` 2.2.12 (peer range `>=5.0.0`) needed no bump.

`telemetry-worker` already pins `typescript ^6.0.3` (an unrelated recent
merge) and has no `vite` dependency at all - left untouched.

## Test / gate results (all local)

- `pnpm -C ui lint` - 0 errors (13 pre-existing i18n key warnings,
unrelated)
- `pnpm -C ui run build` (`vue-tsc --noEmit && vite build`) - passes
- `pnpm -C ui run test:unit` - 271/271 tests passing (29 files)
- `pnpm -C ui run test:coverage` - 89.36% lines (up from 88.58% on
`main`), deterministic across 3 runs
- `cargo check -p driven-app` - passes

Supersedes #121 and #122.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude <noreply@anthropic.com>

Author: pmaxhogan

ui/package.json

@@ -33,7 +33,7 @@
     "@tailwindcss/postcss": "^4.3.2",
     "@types/node": "^26",
     "@vitejs/plugin-vue": "^6.0.8",
-    "@vitest/coverage-v8": "^2.1.0",
+    "@vitest/coverage-v8": "^2.1.9",
     "@vue/test-utils": "^2.4.6",
     "@vue/tsconfig": "^0.9.1",
     "eslint": "^10.7.0",
@@ -43,10 +43,10 @@
     "postcss": "^8.5.16",
     "prettier": "^3.9.4",
     "tailwindcss": "^4.3.2",
-    "typescript": "^5.6.0",
+    "typescript": "^6.0.3",
     "typescript-eslint": "^8.62.1",
-    "vite": "^6.0.0",
-    "vitest": "^2.1.0",
+    "vite": "^8.1.5",
+    "vitest": "^2.1.9",
     "vue-eslint-parser": "^10.0.0",
     "vue-tsc": "^2.1.0"
   },