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>

CLAUDE.md

@@ -20,19 +20,26 @@ When working with issues, pull requests, or other repository operations for this
 When asked to commit changes for this project:
 
 - **Always commit as Hikari** using: `--author="Hikari <hikari@nhcarrigan.com>"`
-- **Always use `--no-gpg-sign`** since Hikari doesn't have GPG signing set up
+- **Always sign commits** with Hikari's GPG key: `--gpg-sign=5380E4EE7307C808`
 - **Never add `Co-Authored-By` lines** for Gitea commits
 - **Always ask for confirmation** before committing
+- **Always ask for confirmation** before pushing
 
 Example commit command:
 
 ```bash
-git commit --author="Hikari <hikari@nhcarrigan.com>" --no-gpg-sign -m "your commit message"
+git commit --author="Hikari <hikari@nhcarrigan.com>" --gpg-sign=5380E4EE7307C808 -m "your commit message"
+```
+
+Example push command:
+
+```bash
+git push https://hikari:TOKEN@git.nhcarrigan.com/nhcarrigan/hikari-desktop.git <branch>
 ```
 
 ## Testing Requirements
 
-All new features, fixes, and significant changes should include tests whenever possible:
+**All changes MUST include tests.** This is non-negotiable — no feature, bug fix, or refactor should be committed without corresponding test coverage. If a change cannot be tested (e.g. pure UI layout, Tauri IPC calls that are impossible to mock), document why in a comment.
 
 - **Frontend tests**: Use Vitest with `@testing-library/svelte` for component tests
 - **Test files**: Place test files next to the code they test with `.test.ts` or `.spec.ts` extension
@@ -130,16 +137,16 @@ describe("FeatureName", () => {
 });
 ```
 
-### Adding Tests for New Features
+### Adding Tests for All Changes
 
-When developing new features, always add corresponding tests:
+Every change — features, bug fixes, refactors — must include tests:
 
 1. **Before implementing**: Consider what needs testing (happy path, edge cases, errors)
 2. **During implementation**: Write tests alongside the code
 3. **After implementation**: Run `pnpm test:coverage` to verify coverage remains high
 4. **Before committing**: Ensure `check-all.sh` passes (includes all tests)
 
-The goal is to maintain our near-100% coverage as the codebase grows, so future refactoring and changes can be made with confidence!
+**Do not commit changes without tests.** The goal is to maintain near-100% coverage as the codebase grows, so future refactoring can be done with confidence!
 
 ## Quality Assurance