v0.9.26

Hotfix on top of v0.9.25. Closes [#797](https://github.com/rohitg00/agentmemory/issues/797).

## Fixed

- **First boot crash: `TypeError: Cannot read properties of undefined (reading 'v')`** (#797). The sharded index load path checked `manifest.value !== null` before forwarding, but some iii-state adapters return `undefined` (not `null`) for a missing key. `loadManifestData(undefined)` then crashed on `undefined.v`. Now treats both null + undefined + non-object values as 'no manifest' and falls through to the legacy load path.

Self-healing was already in place — the next debounced save rebuilt a fresh manifest — but the crash on first boot scared every fresh upgrader.

## Upgrade

```
npm install -g @agentmemory/agentmemory@0.9.26
```

If you already saw the warning on v0.9.25 and the daemon kept running, you're fine — the index was already rebuilt. v0.9.26 just makes the first-run boot quiet.

## Verified

- 125 test files / 1381 tests pass
- Build clean