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.

README.md

@@ -21,7 +21,8 @@ Built because we were tired of stitching together Pinecone + Neo4j + MongoDB and
 ## Install
 
 ```bash
-npm install @soulcraft/brainy
+bun add @soulcraft/brainy        # fastest — recommended
+npm install @soulcraft/brainy    # Node.js — fully supported
 ```
 
 ## Quick Start
@@ -387,10 +388,10 @@ Performance benchmarks and capacity planning in **[docs/PERFORMANCE.md](docs/PER
 
 ## Requirements
 
-**Bun 1.0+** (recommended) or **Node.js 22 LTS**
+**Bun 1.1+** (recommended) or **Node.js 22 LTS**
 
 ```bash
-bun install @soulcraft/brainy    # Bun — best performance
+bun add @soulcraft/brainy        # Bun — best performance
 npm install @soulcraft/brainy    # Node.js — fully supported
 ```