Feature request: Search past sessions by conversation content/topic

Feature Request

Current Behavior

The session picker's search (/ key in /resume) only searches by session name and first prompt. There is no way to search through the full conversation content of past sessions.

Desired Behavior

Allow users to search past sessions by conversation content/topic keywords, not just session name or first prompt.

Use Case

When a user wants to resume a past session but didn't rename it with /rename, they currently have no efficient way to find it by topic. For example:

• "I want to go back to the session where we discussed authentication refactoring" — but the session was never renamed
• The user has to manually preview (P) each session one by one, which is tedious

Proposed Solution

Add a content search mode to the session picker (e.g., a keybinding to toggle between name search and content search), or extend the existing / search to also match against conversation messages.

Additional Context

Session data is already stored locally under ~/.claude/projects/, so indexing or searching through conversation content should be technically feasible.