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/ToolCallBlock.svelte

@@ -0,0 +1,141 @@
+<script lang="ts">
+  interface Props {
+    toolName: string | null;
+    content: string;
+    timestamp: Date;
+  }
+
+  let { toolName, content, timestamp }: Props = $props();
+  let isExpanded = $state(false);
+
+  function toggleExpanded() {
+    isExpanded = !isExpanded;
+  }
+
+  function formatTime(date: Date): string {
+    return date.toLocaleTimeString("en-US", {
+      hour: "2-digit",
+      minute: "2-digit",
+    });
+  }
+</script>
+
+<div class="tool-block">
+  <button class="tool-header" onclick={toggleExpanded} type="button">
+    <span class="tool-timestamp">{formatTime(timestamp)}</span>
+    <svg
+      class="tool-icon"
+      fill="none"
+      stroke="currentColor"
+      viewBox="0 0 24 24"
+      width="16"
+      height="16"
+    >
+      <path
+        stroke-linecap="round"
+        stroke-linejoin="round"
+        stroke-width="2"
+        d="M14.7 6.3a1 1 0 0 0 0 1.4l1.6 1.6a1 1 0 0 0 1.4 0l3.77-3.77a6 6 0 0 1-7.94 7.94l-6.91 6.91a2.12 2.12 0 0 1-3-3l6.91-6.91a6 6 0 0 1 7.94-7.94l-3.76 3.76z"
+      />
+    </svg>
+    {#if toolName}
+      <span class="tool-name">[{toolName}]</span>
+    {/if}
+    <span class="tool-label">{content}</span>
+    <svg
+      class="chevron"
+      class:expanded={isExpanded}
+      fill="none"
+      stroke="currentColor"
+      viewBox="0 0 24 24"
+      width="14"
+      height="14"
+    >
+      <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M19 9l-7 7-7-7" />
+    </svg>
+  </button>
+
+  {#if isExpanded}
+    <div class="tool-content">
+      {content}
+    </div>
+  {/if}
+</div>
+
+<style>
+  .tool-block {
+    margin-bottom: 0.5rem;
+    border: 1px solid var(--border-color);
+    border-radius: 0.375rem;
+    background: var(--bg-secondary);
+    opacity: 0.85;
+  }
+
+  .tool-header {
+    display: flex;
+    align-items: center;
+    gap: 0.5rem;
+    width: 100%;
+    padding: 0.5rem 0.75rem;
+    border: none;
+    background: transparent;
+    cursor: pointer;
+    color: var(--terminal-tool, #c084fc);
+    font-size: 0.875rem;
+    transition: all 0.2s;
+  }
+
+  .tool-header:hover {
+    background: var(--bg-primary);
+    color: var(--text-primary);
+  }
+
+  .tool-timestamp {
+    font-family: monospace;
+    font-size: 0.75rem;
+    opacity: 0.7;
+    color: var(--text-secondary);
+    flex-shrink: 0;
+  }
+
+  .tool-icon {
+    flex-shrink: 0;
+  }
+
+  .tool-name {
+    font-family: monospace;
+    font-weight: 600;
+    flex-shrink: 0;
+    color: var(--terminal-tool-name, #ddd6fe);
+  }
+
+  .tool-label {
+    flex: 1;
+    text-align: left;
+    font-style: italic;
+    overflow: hidden;
+    text-overflow: ellipsis;
+    white-space: nowrap;
+  }
+
+  .chevron {
+    flex-shrink: 0;
+    transition: transform 0.2s;
+  }
+
+  .chevron.expanded {
+    transform: rotate(180deg);
+  }
+
+  .tool-content {
+    padding: 0.75rem;
+    border-top: 1px solid var(--border-color);
+    color: var(--terminal-tool, #c084fc);
+    font-family: monospace;
+    font-size: 0.875rem;
+    font-style: italic;
+    line-height: 1.5;
+    white-space: pre-wrap;
+    word-break: break-word;
+  }
+</style>