Bug Description

PGLite-based gbrain commands crash immediately with:

PGLite failed to initialize its WASM runtime.
  This is most commonly the macOS 26.3 WASM bug: https://github.com/garrytan/gbrain/issues/223
  Run \`gbrain doctor\` for a full diagnosis.
  Original error: ENOENT: no such file or directory, open '/$$bunfs/root/pglite.data'.

Unlike issue #223 (which is macOS 26.3 specific), this occurs on macOS 12.7.6 (Darwin 21H1320).

Steps to Reproduce

1. `gbrain sync --skip-failed`
2. `gbrain sources list`
3. `gbrain apply-migrations --yes`
4. Any command that triggers `engine.connect()`

All crash with the same PGLite WASM initialization error.

Commands that work: `gbrain doctor --fast` (skips DB connection check).

Environment

• macOS: 12.7.6 (Darwin 21H1320, macOS Monterey)
• Bun: 1.3.14
• Node: v24.14.1
• gbrain: 0.40.8.0 (source build) and 0.40.2.0 (official binary)
• PGLite: 0.4.3
• Architecture: arm64 (Apple Silicon)

Analysis

The error path `/$$bunfs/root/pglite.data` is a Bun virtual filesystem mount point. On this macOS version, `/$$bunfs/root` is a read-only directory:

$ ls / | grep bunfs
# → nothing (directory does not exist or is empty/mounted as read-only)

$ mkdir -p /$$bunfs/root
# → mkdir: /$$bunfs: Read-only file system

This means PGLite cannot write its `pglite.data` file during `PGlite.create()`, causing immediate Abort.

`gbrain doctor` works because the `--fast` flag skips the DB connection phase entirely.

Expected Behavior

PGLite should initialize successfully, or gbrain should detect this path issue and fall back gracefully.

Additional Context

• Issue PGLite WASM crash on macOS 26.3 with Bun 1.3.11 #223 mentions macOS 26.3, but this machine is on macOS 12.7.6
• Tested with both official gbrain binary (0.40.2.0) and source-built binary (0.40.8.0) — both fail
• Tested with `bun run src/cli.ts` (direct source) — also fails
• `/$$bunfs/root` being read-only appears to be the root cause