fix(session): preserve time_updated on project_id migration

[divitkashyap]

Issue for this PR

Closes #25392

Type of change

• Bug fix

What does this PR do?

Two bulk UPDATE statements in project.ts rewrite session.project_id without touching time_updated:

1. Project.fromDirectory — moves sessions from the global project into a real project when their directory matches (runs every time you open a project).
2. Project.migrateProjectId — moves sessions when a project's ID changes (e.g. directory rename).

Because time_updated has Drizzle's .$onUpdate(() => Date.now()) hook, every row touched by those UPDATEs gets its time_updated stamped to the current time. Net effect for users with any legacy global-scoped sessions: /sessions shows every old session with today's date on every startup.

Fix: pass the column through unchanged via sql\${SessionTable.time_updated}`, which makes Drizzle skip the auto-update. Same pattern that projectors.ts(PR #27094) anddata-migration.ts` already use elsewhere in the file.

How did you verify your code works?

Extended the existing regression test in test/project/migrate-global.test.ts — captures time_updated before calling fromDirectory, then asserts it is identical after. Confirmed the test fails without the fix (the column drifts by tens of ms) and passes with it.

$ bun test test/project/migrate-global.test.ts
 4 pass
 0 fail

Also verified directly against a local DB:

sqlite3 ~/.local/share/opencode/opencode.db \
  "SELECT id, datetime(time_updated/1000, 'unixepoch') FROM session ORDER BY time_updated DESC LIMIT 10"

Before the fix: every recently-opened project's sessions cluster on the launch timestamp. After: the historical timeline is preserved.

bun turbo typecheck --filter opencode passes.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[divitkashyap]

@nexxeln this is a follow-up to your #27094 — same root cause ($onUpdate firing on bulk writes), but two Project.* paths still lacked the preserve clause. Repro and confirmation are in the test (it fails on dev, passes with the change). Happy to adjust if you would prefer the preserve logic encapsulated differently.