security: bound unauthenticated BLE state

[enaboapps]

Closes #658

Changes

• cap concurrent partial messages and pending pairings at eight
• cap frame, request, device, desktop, and nonce identifiers at 128 UTF-8 bytes
• reject oversized, empty, over-aggregate, and impossible chunks before they grow state
• preserve same-device pairing replacement at a full queue and protocol v1 behavior

Validation

• npm lint, tests, build, and audit
• app Rust fmt, Clippy, and 229 tests including BLE flood and boundary cases
• verifier and startup-launcher fmt, Clippy, tests, and Cargo audits
• unsigned Windows UIAccess installer rebuild and verification