Windows: investigate `restart_service` crash blocking component-load test paths

## Context

While trying to expand Windows integration test coverage (#525, #546, #547), the actual underlying blocker came into focus. Multiple integration test files have per-test skips for `restart_service` operations with the same explanation:

> `'Windows: Skipping restart_service to avoid crash'`

Found in:
- `integrationTests/apiTests/tests/23_blob.mjs` (2 occurrences)
- Likely elsewhere — `grep -rE "Windows.*Skipping restart_service|restart_service.*crash"` for the full set

These skips look surgical and isolated but they're load-bearing in suite flow: any test that needs Harper to pick up a newly-written component file depends on `restart_service` to actually load it. With the operation skipped, downstream tests fail with "schema not found" / "component not loaded" cascades.

This was the latent root cause behind #546/#547. The outer suite-level skip on `23_blob.mjs` (`{ skip: process.platform === 'win32' }`) is effectively a workaround for this — undocumented, but real.

See HarperFast/harper#547 (closed) for the cascade trace: the file-write portion of the blob suite passes on Windows, then "Confirm Blob schema and table created" fails because the schema isn't there, because the component was never loaded, because `restart_service` was skipped.

## Goal

Make `restart_service` work on Windows, OR replace the operation in the test paths with a Windows-compatible alternative that achieves the same effect (Harper picks up a newly-written component).

## Approach (suggested)

1. **Reproduce the crash locally on Windows.** Run a minimal test that calls `restart_service` (e.g., one of the currently-skipped tests in `23_blob.mjs`). Capture the actual crash signature — stack trace, exit code, hdb.log output.
2. **Identify the failure mode.** Likely candidates based on Kris's prior Windows fixes:
- File-locking / EPERM during the restart sequence (`7823d97a` "workaround database drop crashes on windows" suggests this pattern is present)
- Worker-process spawn ordering specific to Windows process semantics
- Socket / pipe handling for IPC during the restart handshake
- Database file handles not released cleanly across the restart
3. **Fix or work around.** Either fix the crash in Harper itself, or introduce a Windows-specific code path (e.g., separate-process restart, retry-with-backoff on EPERM, explicit file-handle release before restart).
4. **Un-skip the affected tests.** Once `restart_service` works on Windows, remove the `'Windows: Skipping restart_service to avoid crash'` skips. The outer suite-level skip on `23_blob.mjs` becomes removable as a follow-up — that work is well-covered by #546's framing, just gated on this issue first.

## Success criteria

- A Windows integration test can successfully call `restart_service` and observe the newly-loaded component active after the call.
- The `'Windows: Skipping restart_service to avoid crash'` skips can be removed from `23_blob.mjs` (and any other files with the same pattern).
- `run-integration-apiTests-windows` CI job continues to pass.

## Out of scope

- Un-skipping the broader `23_blob.mjs` suite — that's #546's territory, gated on this issue.
- Other Windows skips unrelated to `restart_service` (e.g., `8_deleteTests.mjs` "Windows does not allow `*` in directory names" — that's a fundamentally different OS-semantic mismatch).

## References

- PR #547 (closed) — cascade diagnosis showing the load-bearing dependency
- Issue #546 (closed) — superseded by this; same goal but blocked on `restart_service`
- Issue #525 (Kris's original) — broader Windows expansion framing
- PR #528 (merged) — Kris's prior Windows fixes
- Related Windows commits: `7823d97a`, `a9f55dc4`, `aa034530`, `351d1a40`

(🤖)

Start by reproducing the Windows crash with a minimal restart_service call from integrationTests/apiTests/tests/23_blob.mjs, then use the suggested grep command and inspect the crash signature, exit code, and hdb.log. Done means a Windows integration test observes the newly written component after restart_service, the matching skips can be removed, and run-integration-apiTests-windows passes.

Written by the indexing model from the issue text.