Chat loses an unsent draft on reload #453

Part of #86.

What the user sees: text typed in Chat (Community or a direct conversation) but not sent is gone after a page reload. The Assistant keeps its draft; Chat does not keep drafts at all. Seen on installed alpha.21 and alpha.22 (a plain reload with no update also drops it): #84 (comment)

Done means

• An unsent Chat draft (Community and direct) is still there after a reload and after unlock, per conversation, the way the Assistant draft is kept.
• Sending or clearing the draft removes the saved copy.
• A source test fails before the fix and passes after; one installed check on the current alpha records the result here.