/resume list drops recent sessions — should sort by most recent first

[Golnaz89]

Describe the feature or problem you'd like to solve

Recent sessions are missing from the /resume list. Sessions created within the same day — even within the last hour — don't appear, requiring manual ID lookups via the session store. There's no way to search or filter sessions either.

Proposed solution

Sort the /resume list strictly by recency. Pin all of today's sessions at the top and only cap/paginate older ones. Add a keyword search option (e.g., /resume --search budget) to find sessions without needing the exact ID.

Example prompts or workflows

1. User has 3 sessions today — opens /resume and expects to see all 3 at the top. Currently, one or more may be missing.
2. User wants to resume a session about "Topic X" but it's not in the list. They have to ask Copilot to query the session store for the ID, then manually run /resume .
3. With the fix: /resume always shows today's sessions first. User can also run /resume --search Topic X to instantly find it.

Additional context

No response