chore(8.0): modernize toolchain + position Bun as a runtime

Consumer-invisible modernization pass — no public API or runtime-behavior
change; dist for the override-only files is byte-identical.

Toolchain:
- CI: GitHub Actions matrix — Node 22/24 (test:unit) + Bun latest (test:bun).
- engines: node ">=22" (was "22.x"), bun ">=1.1.0".
- tsconfig: isolatedModules + noImplicitOverride; add the 33 `override`
  modifiers the flag requires across storage/integrations/vfs/transaction.
- deps: @types/node ^22; add prettier; drop dead standard-version,
  @rollup/plugin-* and the redundant embedded eslintConfig (flat
  eslint.config.js is the active config — verified identical lint output).

paramValidation: replace the top-level `await import('node:os'/'node:fs')`
with static ESM imports. The top-level-await form poisoned the module graph;
static imports also drop the browser/edge fallback branches no supported
runtime reaches (8.0 is Node/Bun/Deno-only).

Bun positioning: recommend Bun as a runtime (`bun add` / `bun run`), which is
green (test:bun 8/8). Drop single-binary `bun build --compile` as a target —
native addons cannot embed into it, and Bun 1.3.10 has a `--compile` codegen
regression around top-level await. Rename the Bun test to bun-runtime-test.ts
and correct docs that overclaimed single-binary support.

Gates: typecheck 0, build 0, test:unit 1743/1743, test:bun 8/8.

.github/workflows/ci.yml

@@ -0,0 +1,38 @@
+name: CI
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  node:
+    name: Node ${{ matrix.node-version }}
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        node-version: ['22', '24']
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node-version }}
+          cache: npm
+      - run: npm ci
+      - run: npm run test:unit
+
+  bun:
+    name: Bun (latest)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: '22'
+          cache: npm
+      - uses: oven-sh/setup-bun@v2
+        with:
+          bun-version: latest
+      - run: npm ci
+      # Bun as a runtime is the supported Bun story (`bun add` / `bun run`).
+      - run: npm run test:bun