fix(ui): preserve time_updated when renaming session title

[0xSkybreaker]

The Drizzle ORM Timestamps definition uses $onUpdate(() => Date.now()), which automatically bumps time_updated on every row update. When renaming a session via the sessions dialog (ctrl+R), this caused the renamed session to move to "Today" in the session list because setTitle only passed the new title without preserving the original timestamp.

Root Cause

time_updated in packages/opencode/src/storage/schema.sql.ts has .$onUpdate(() => Date.now()), which fires on every UPDATE to any table using Timestamps. The setTitle method only patched { title }, allowing the ORM to auto-set time_updated to the current time.

Fix

setTitle now reads the session first and explicitly passes the original time_updated value in the patch. Drizzle ORM's $onUpdate only fires when no explicit value is provided, so this preserves the original timestamp.

Reproduction

1. Open the sessions dialog (/sessions)
2. Select a session from a previous day
3. Press ctrl+R to rename it
4. The renamed session no longer moves to Today

Fixes #1257