Prepare Maple Research 3.4.4 build train

[AnthonyRonning]

Prepare the next Maple Research build train at 3.4.4 after the completed 3.4.3 release. Update the frontend, native app and Apple version fields consistently, advance Android versionCode from 2000028026 to 2000028027, and update only the app version entry in Cargo.lock.

Generated with the standard pinned just update-version 3.4.4 helper from master c61712a16a925d360a25a6b75ca9e74aefdcf198 in an isolated managed workspace. No runtime or dependency changes.

Validation:

• Helper Cargo check and release validator v3.4.4 passed.
• Exact six-file diff, Apple version parity, Android monotonic increment and git diff --check passed.
• nix flake check --no-update-lock-file: all 12 aarch64-darwin checks passed; incompatible systems omitted by Nix.
• Normal pre-commit frontend/native gates passed; 1,241 frontend tests passed; native tests: 419 library plus 3 CLI passed, 2 existing ignored.

Merge starts the normal signed Research builds and TestFlight pipelines for the next version. This PR prepares the train; it does not create a 3.4.4 tag/GitHub release or submit anything to Apple/Google. The submitted 3.4.3 artifacts are unchanged.

[github-actions]

Maple development preview: https://221e96c1.maple-ca8.pages.dev

Commit: fed80c227109212a165b63b4ced02a5ef1560f5e

Uses development API, billing, flags and PCR configuration. Cloudflare Access applies.