Allow renaming terminal tabs (persisted per project)

Right-click a tab (or double-click) to rename. Renamed labels show
as "ProjectName: CustomName" and are stored in the project's
renamed_session_names map. The entry is cleared on tab close.

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

app/src/lib/types.ts

@@ -37,6 +37,7 @@ export interface Project {
   claude_instructions: string | null;
   enabled_mcp_servers: string[];
   claude_code_settings: ClaudeCodeSettings | null;
+  renamed_session_names: Record<string, string>;
   created_at: string;
   updated_at: string;
 }