add Claude session storage view with user-driven cleanup

The claude.session-storage command opens a modal listing the workspace's
session transcripts with their on-disk sizes (the <id>.jsonl plus the
<id>/ subagents dir) and a total. Each row deletes with a deliberate
two-click confirm; deletion is guarded against unsafe ids and clide never
removes transcripts on its own. SessionSummary gains a sizeBytes field and
session_index gains formatBytes + deleteSession.

T-148.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -18,6 +18,10 @@ heading, and (b) bumping `pubspec.yaml` `version:` in the same commit.
 
 ### Added
 
+- Claude session storage view (T-148) — the `claude.session-storage`
+  command opens a modal listing the workspace's session transcripts with
+  their on-disk sizes and a total, each removable with a two-click
+  confirm. User-driven only; clide never deletes transcripts on its own.
 - Slash-command typeahead in the Claude composer (T-152) — typing `/`
   (anywhere in the message, not just at the start) pops a list of
   matching commands and skills sourced from the Claude environment;