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/components/InputBar.svelte

@@ -1011,7 +1011,7 @@ User: ${formattedMessage}`;
           : "Connect to Claude first..."}
         disabled={isSubmitting}
         rows={1}
-        style="height: {textareaHeight}px; font-size: var(--terminal-font-size, 14px);"
+        style="height: {textareaHeight}px; font-size: var(--terminal-font-size, 14px); font-family: var(--terminal-font-family, monospace);"
         class="w-full px-4 py-3 bg-[var(--bg-secondary)] border border-[var(--border-color)]
              rounded-lg text-[var(--text-primary)] placeholder-gray-500 resize-none
              input-trans-focus disabled:opacity-50 disabled:cursor-not-allowed"