release(v4.4.0): public accessor for device identity public key

Expose the local device's 32-byte Ed25519 identity public key on Shade
so apps can hand it to their own backend at enrollment time for
signature verification, key pinning or per-device safety-number
computation. Closes the gap that forced consumers to ship placeholder
random bytes their backend could store but never verify against.

- @shade/sdk Shade.identityPublicKey: Promise<Uint8Array> — getter
  mirrors the existing fingerprint accessor. Throws pre-init,
  reflects the current key after rotate(), retired key preserved in
  retired-identities storage per existing grace-period contract.
  Private key remains unreachable.
- Test in shade-sdk/tests/sdk.test.ts: round-trip match against the
  underlying storage's signingPublicKey, plus value updates after
  rotate().
- Lockstep version bump 4.3.0 → 4.4.0 across all 25 packages.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -5,6 +5,35 @@ All notable changes to Shade are documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [4.4.0] — 2026-05-05 — Public accessor for the device's identity public key
+
+Browser-based Shade consumers building enrollment flows had no way to
+hand the device's actual Ed25519 identity public key to their own
+backend — the key was reachable only via the private
+`storage.getIdentityKeyPair()` call inside `Shade`. Apps shipped with
+placeholder bytes (`crypto.getRandomValues(new Uint8Array(32))`) that
+the backend stored but couldn't verify against, deferring real
+cryptographic device binding until the SDK exposed the key.
+
+### Added
+
+#### `@shade/sdk`
+- `Shade.identityPublicKey: Promise<Uint8Array>` — getter returning the
+  local device's 32-byte Ed25519 identity public key. Mirrors the
+  `fingerprint` accessor shape. Throws if accessed before
+  `initialize()`. Reflects the current key after `rotate()`; the
+  previous key remains in retired-identities storage for the
+  configured grace period. Use `fingerprint` (12-group safety number)
+  for human side-channel comparison; use `identityPublicKey` when
+  handing the raw key to a backend for signature verification or
+  pinning.
+
+### Tests
+- `packages/shade-sdk/tests/sdk.test.ts` — `identityPublicKey exposes
+  the device Ed25519 key and tracks rotation` covers the round-trip
+  match against the underlying storage and that the value updates
+  after `rotate()`.
+
 ## [4.3.0] — 2026-05-05 — Browser persistence via `@shade/storage-indexeddb`
 
 Browser-based Shade consumers had no path to session persistence: the only