v4.0.5.0 - Platytalk crypto interop

Platytalk End-to-End Encryption Fixes

Critical fixes

• Cross-curve interop: web client now auto-detects peer's EC curve (P-256 / P-384 / P-521) from SPKI bytes and matches the ephemeral. Resolves "Send failed @ import-peer-pub" between desktop (was P-521) and iOS Safari/Edge.
• Desktop ECDH pinned to P-256: ECDiffieHellman.Create() was defaulting to nistP521 on Windows; new identity keys are now uniformly P-256. Existing P-521 keys still work via curve-detect.
• iOS WebKit data-coercion: all SubtleCrypto inputs are coerced to fresh ArrayBuffers via toAB() to satisfy WebKit's stricter parser.

Mobile UI

• Chat header title now wraps onto its own row above the action buttons (no more single-character vertical rendering).

Diagnostics

• Send and decrypt failures now surface inline with stage info instead of silently disappearing.
• Service worker bumped to ptk-sw-v6-decrypt-toast to invalidate old caches.