feat: multiple UI improvements, font settings, and memory file display names (#175)

## Summary

- **fix**: `show_thinking_blocks` setting now persists across sessions — it was defined on the TypeScript side but missing from the Rust `HikariConfig` struct, so serde silently dropped it on every save/load
- **feat**: Tool calls are now rendered as collapsible blocks matching the Extended Thinking block aesthetic, replacing the old inline dropdown approach
- **feat**: Add configurable max output tokens setting
- **feat**: Use random creative names for conversation tabs
- **test**: Significantly expanded frontend unit test coverage
- **docs**: Require tests for all changes in CLAUDE.md
- **feat**: Allow users to specify a custom terminal font (Closes #176)
- **feat**: Display friendly names for memory files derived from the first heading (Closes #177)
- **feat**: Add custom UI font support for the app chrome (buttons, labels, tabs)
- **fix**: Apply custom UI font to the full app interface — `.app-container` was hardcoded, blocking inheritance from `body`; also renamed "Custom Font" to "Custom Terminal Font" for clarity

✨ This PR was created with help from Hikari~ 🌸

Reviewed-on: #175
Co-authored-by: Hikari <hikari@nhcarrigan.com>
Co-committed-by: Hikari <hikari@nhcarrigan.com>

src/lib/commands/slashCommands.ts

@@ -63,6 +63,7 @@ async function changeDirectory(path: string): Promise<void> {
         allowed_tools: allAllowedTools,
         use_worktree: config.use_worktree ?? false,
         disable_1m_context: config.disable_1m_context ?? false,
+        max_output_tokens: config.max_output_tokens ?? null,
       },
     });
 
@@ -139,6 +140,7 @@ async function startNewConversation(): Promise<void> {
         allowed_tools: allAllowedTools,
         use_worktree: config.use_worktree ?? false,
         disable_1m_context: config.disable_1m_context ?? false,
+        max_output_tokens: config.max_output_tokens ?? null,
       },
     });