Local Secrets Store secrets are persisted in plaintext on disk

### What versions & operating system are you using?

Wrangler: 4.70.0
Operating system: macOS

### Please provide a link to a minimal reproduction

https://github.com/orelbn/cloudflare-local-secrets-store-plaintext-repro

### Describe the Bug

Local-only Secrets Store secrets created without `--remote` are persisted in plaintext on disk.

I expected local Secrets Store secrets to either:
1. be encrypted at rest locally, or
2. be clearly documented as plaintext-accessible local development state

Right now, the local persistence behavior appears to store secret values in plaintext under `.wrangler/state`.

### Reproduction

Minimal reproduction repo:
https://github.com/orelbn/cloudflare-local-secrets-store-plaintext-repro

From the repo root, run:

```bash
wrangler secrets-store secret create test-store \
--name TEST_SECRET \
--value 'UNIQUE_CF_SECRET_9d3f4b6e' \
--scopes workers
```

```bash
rg -n 'UNIQUE_CF_SECRET_9d3f4b6e' .wrangler/state
```

Actual behavior
The plaintext secret value is found in the local persisted files under .wrangler/state.

Expected behavior

Either:
* local-only Secrets Store secrets should be encrypted at rest locally, or
* the docs should explicitly state that local-only Secrets Store persistence is not encrypted and should not be treated as a secure local vault

Relevant documentation:

[Manage account secrets](https://developers.cloudflare.com/secrets-store/manage-secrets/)

### Please provide any relevant error logs

_No response_