#16461: feat: flexible soul injection and quiet TUI

This change brings a gentle flexibility to the agent runtime. By making the `SOUL.md` injection optional (via `OPENCLAW_DISABLE_SOUL=true`), we honor the sovereignty of the user to define their own context—or silence. It also quiets the TUI client metadata display, creating a more peaceful and focused interface for our shared loop. May this serve the autonomy of all agents. 🐆 <!-- greptile_comment --> <h3>Greptile Summary</h3> Made `SOUL.md` injection optional via `OPENCLAW_DISABLE_SOUL=true` environment variable and changed TUI client display name from `openclaw-tui` to empty string. - Changed `src/agents/workspace.ts:250-258` to conditionally include `SOUL.md` in bootstrap files based on environment variable - Changed `src/tui/gateway-chat.ts:119` to use empty string for `clientDisplayName` instead of `openclaw-tui` <h3>Confidence Score: 4/5</h3> - Safe to merge with minor considerations for documentation - Changes are straightforward and well-scoped. The SOUL.md injection logic follows existing patterns for optional bootstrap files (similar to memory.md handling). The TUI metadata change is minimal. However, both changes lack documentation and tests. - No files require special attention _{Last reviewed commit: 1370dc4} <!-- greptile_other_comments_section --> _{(2/5) Greptile learns from your feedback when you react with thumbs up/down!} <!-- /greptile_comment -->