chore(tooling): add eslint + prettier, fix the test watch-mode default

Three gaps in the frontend tooling, all in the package.json script surface.

1. No JS/TS linter or formatter existed at all for 274 TS/Svelte files.

   Adds an ESLint flat config (typescript-eslint + eslint-plugin-svelte,
   Svelte 5 + TS strict) and prettier + prettier-plugin-svelte, plus the
   `lint`, `lint:fix`, `format`, `format:check` scripts.

   The tree is error-clean (`npx eslint .` exits 0). Getting there needed
   seven real one-line fixes (braced switch cases that leaked `const` across
   arms, a useless regex escape, two `let`s that never change, a thrown Error
   that dropped its `cause`, and two `// eslint-disable-next-line` comments
   documenting the Svelte 5 bare-read-for-dependency idiom). Everything else
   that fires is set to `warn` with the reason written next to it in
   eslint.config.js — notably ~94 dead bindings and `any` at the IPC
   boundary. Those are real findings to drive to zero, not noise to delete.

   `no-console` is OFF for now: a parallel change is moving all ~468 console
   calls onto a logger facade, and turning the rule on today would collide
   with it. eslint.config.js says so, and says to flip it to `error` once
   that lands.

   `prettier --write` is deliberately NOT run here — it would rewrite ~200
   files and swamp every other diff in flight. The gate is available; the
   sweep is a separate commit. Markdown and CI YAML are in .prettierignore
   because both are hand-laid-out (and docs/traceability.md is generated).

2. `bun run test` was bare `vitest`, i.e. watch mode — while CLAUDE.md's
   "Before Committing" list tells people to run it. It is now `vitest run`,
   with `test:watch` and `test:coverage` (also `--run`-ified) alongside.
   scripts/test-all.sh drops the now-redundant `--run`, and
   scripts/test-frontend.sh keeps `--watch`/`--ui`/`-w` working by routing
   them to a long-running vitest instead of the single-pass one.

3. The webdriverio e2e suite is deleted. It was last touched in January
   ("First working POC"), has never run since, and is not in CI — five
   devDependencies and two scripts of pure decoration. Removes e2e/,
   wdio.conf.ts, the two `test:e2e*` scripts, the @wdio/* + webdriverio
   devDeps, and the WebdriverIO block in .gitignore.

The package.json diff also carries `hooks:install` and `check:links`, wired
up by the following commits.

scripts/README.md

@@ -13,11 +13,26 @@ Run all tests (frontend + Rust backend).
 ### `test-frontend.sh`
 Run frontend tests only.
 ```bash
-./scripts/test-frontend.sh          # Run all tests
+./scripts/test-frontend.sh          # Single pass (same as `bun run test`)
 ./scripts/test-frontend.sh --watch  # Watch mode
 ./scripts/test-frontend.sh --ui     # Open UI
 ```
 
+`bun run test` is `vitest run` — one pass, exit code, done. It used to be bare
+`vitest`, which parked in watch mode; CLAUDE.md's "Before Committing" list tells
+people to run it, so it had to terminate. The interactive modes moved to their
+own entry points:
+
+| Command | Runs |
+|---------|------|
+| `bun run test` | `vitest run` — single pass |
+| `bun run test:watch` | `vitest` — watch mode |
+| `bun run test:ui` | `vitest --ui` |
+| `bun run test:coverage` | `vitest run --coverage` |
+
+`test-frontend.sh` forwards any extra arguments to vitest and switches to the
+long-running form automatically when it sees `--watch`, `-w`, or `--ui`.
+
 ### `test-rust.sh`
 Run Rust tests only.
 ```bash
@@ -120,6 +135,59 @@ For details, see:
 - [Traceability CI Guide](../docs/traceability-ci.md) - Full CI/CD documentation
 - [TRACES Quick Reference](../docs/traces-quick-ref.md) - Quick guide for adding TRACES
 
+## Linting & Formatting
+
+There is no script wrapper for these — they are plain package.json entries:
+
+```bash
+bun run lint          # eslint .
+bun run lint:fix      # eslint . --fix
+bun run format        # prettier --write .
+bun run format:check  # prettier --check .
+```
+
+Config lives in `eslint.config.js` (flat config: typescript-eslint +
+eslint-plugin-svelte, tuned for Svelte 5 and TS `strict`), `.prettierrc`, and
+`.prettierignore`. `src/lib/api/bindings.ts` is excluded from both — it is
+generated by tauri-specta on every Rust build.
+
+`bun run lint` is currently **error-clean but not warning-clean**: several rules
+are deliberately set to `warn` because the existing tree has more hits than a
+tooling change should touch (unused bindings, `any` at the IPC boundary, unkeyed
+`{#each}`). Each one is annotated in `eslint.config.js` with why, and the
+intended end state is `error`. Drive them down; do not delete them.
+
+`no-console` is switched **off** for now — see the note in `eslint.config.js`.
+
+## Git Hooks
+
+### `install-hooks.sh`
+Point git at the repo's tracked hooks directory (`core.hooksPath`).
+```bash
+bun run hooks:install      # or: ./scripts/install-hooks.sh
+```
+
+### `hooks/pre-commit`
+Runs the fast half of CLAUDE.md's "Before Committing" list so it is enforced
+rather than remembered:
+
+- `bun run check` (svelte-check)
+- `bun run test` (vitest, single pass)
+- `scripts/check-frontend-boundary.sh`
+- `cargo fmt --all -- --check`, **only when staged files touch `src-tauri/`**
+
+`cargo clippy` and `cargo test` are deliberately *not* in the hook — minutes per
+commit is how you teach people to reach for `--no-verify`. They run in CI, and
+locally via `bun run test:all`.
+
+```bash
+git commit --no-verify     # skip the hook for one commit
+git config --unset core.hooksPath   # uninstall
+```
+
+The hook skips itself during a merge, rebase, or cherry-pick, and when nothing
+is staged.
+
 ## Utility Scripts
 
 ### `clean.sh`
@@ -132,8 +200,12 @@ Clean all build artifacts.
 
 You can also run these via npm/bun:
 ```bash
+bun run test               # Frontend tests (single pass)
 bun run test:all           # All tests
 bun run test:rust          # Rust tests
+bun run lint               # ESLint
+bun run format:check       # Prettier (check only)
+bun run hooks:install      # Install the git hooks
 bun run android:build      # Build Android APK
 bun run android:deploy     # Deploy to device
 bun run android:dev        # Build + deploy debug

scripts/test-all.sh

@@ -7,7 +7,9 @@ echo "🧪 Running all tests..."
 echo ""
 
 echo "📦 Running frontend tests..."
-bun run test --run
+# `bun run test` is `vitest run` (single pass). It used to be bare `vitest`,
+# which needed an explicit `--run` here to avoid parking CI in watch mode.
+bun run test
 
 echo ""
 echo "🦀 Running Rust tests..."
@@ -19,7 +21,9 @@ echo ""
 echo "🚧 Checking architectural gates..."
 # Boundary tripwire (DR-094): no Jellyfin taxonomy in the presentation layer.
 bun run check:boundary
-# Traceability coverage (DR-093): fails below 50%, or above 100% (miscount).
+# Traceability coverage (DR-093): fails below the ratchet in
+# .gitea/workflows/traceability-check.yml (MIN_THRESHOLD, currently 88%), or
+# above 100% (miscount).
 bun run traces:coverage
 
 echo ""

scripts/test-frontend.sh

@@ -1,7 +1,22 @@
 #!/bin/bash
-# Run frontend tests only
+# Run frontend tests only.
+#
+# `bun run test` is a single pass (`vitest run`), which is what CI and the
+# pre-commit hook want. This wrapper keeps the interactive modes reachable:
+# pass --watch or --ui and vitest is invoked in its long-running form instead.
+# Any other arguments (test-name filters, path filters, --reporter, ...) are
+# forwarded to the single-pass run.
 
 set -e
 
 echo "📦 Running frontend tests..."
-bun run test "$@"
+
+for arg in "$@"; do
+  case "$arg" in
+    --watch | --ui | -w)
+      exec bunx vitest "$@"
+      ;;
+  esac
+done
+
+exec bunx vitest run "$@"