Surface tool-call names without adding a permanent subtitle or badge to
every call.

- Keep nonblank titles as the primary label. Blank or whitespace-only
titles fall back to the exact programmatic tool name, then to "Tool
call" if no usable name is available.
- Preserve real titles on name-only updates, and let later title updates
replace a fallback. Fallback names render literally and remain
searchable; exports escape them at the Markdown boundary.
- Show `Tool: <name>` on existing non-terminal tool icons. Keep the
terminal command layout unchanged, and preserve the existing Go to File,
Interrupted Edit, and Copy Command interactions.
- Apply the same behavior to native and external agents, without an
ACP-beta gate.

Release Notes:

- N/A