fix(acp): use tool id as permission cache key instead of command string

[bug-ops]

Problem

Allow always for bash tool calls had no effect — every distinct command
triggered a new permission prompt regardless of prior decisions.

Root Cause

terminal.rs set ToolCallUpdateFields::title to the full command string
(gh api repos/.../contents/docs --jq '...'). The permission cache in
AcpPermissionGate keys on title, so each unique command was a separate
cache entry. Selecting Allow always saved one specific command string but
never matched subsequent calls.

Fix

• title is now set to the stable tool id ("bash")
• The full command moves to raw_input and remains visible in the IDE's
  "View Raw Input" panel
• A single Allow always for bash now covers all shell invocations

Test plan

• cargo clippy -p zeph-acp -- -D warnings passes
• All 133 unit tests in zeph-acp pass
• Manual: allow bash once, trigger another bash call — no prompt
• Manual: allow bash always, restart session — no prompts for any command