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/MemoryBrowserPanel.test.ts

@@ -0,0 +1,98 @@
+import { describe, it, expect } from "vitest";
+
+// Mirror pure logic functions from MemoryBrowserPanel.svelte
+
+interface MemoryFileInfo {
+  path: string;
+  heading: string | null;
+}
+
+function getFileName(path: string): string {
+  return path.split("/").pop() || path;
+}
+
+function getDisplayName(file: MemoryFileInfo): string {
+  return file.heading ?? getFileName(file.path);
+}
+
+describe("getFileName", () => {
+  it("extracts the filename from an absolute Unix path", () => {
+    expect(getFileName("/home/naomi/.claude/projects/foo/memory/MEMORY.md")).toBe("MEMORY.md");
+  });
+
+  it("extracts the filename from a nested path", () => {
+    expect(getFileName("/home/naomi/.claude/projects/foo/memory/debugging.md")).toBe(
+      "debugging.md"
+    );
+  });
+
+  it("returns the path itself when there is no slash", () => {
+    expect(getFileName("MEMORY.md")).toBe("MEMORY.md");
+  });
+
+  it("returns the path when the path ends with a slash (empty filename)", () => {
+    // split('/').pop() returns '' for trailing slash → falls back to full path
+    expect(getFileName("/some/dir/")).toBe("/some/dir/");
+  });
+
+  it("handles single-component paths", () => {
+    expect(getFileName("notes.md")).toBe("notes.md");
+  });
+
+  it("handles Windows-style paths passed as Unix strings", () => {
+    // If the path contains no forward slashes, the whole string is the filename
+    expect(getFileName("C:\\Users\\naomi\\memory\\file.md")).toBe(
+      "C:\\Users\\naomi\\memory\\file.md"
+    );
+  });
+});
+
+describe("getDisplayName", () => {
+  it("returns the heading when the file has one", () => {
+    const file: MemoryFileInfo = {
+      path: "/home/naomi/.claude/projects/foo/memory/MEMORY.md",
+      heading: "Hikari Desktop - Memory",
+    };
+    expect(getDisplayName(file)).toBe("Hikari Desktop - Memory");
+  });
+
+  it("falls back to the filename when heading is null", () => {
+    const file: MemoryFileInfo = {
+      path: "/home/naomi/.claude/projects/foo/memory/debugging.md",
+      heading: null,
+    };
+    expect(getDisplayName(file)).toBe("debugging.md");
+  });
+
+  it("falls back to the filename when heading is an empty string stored as null", () => {
+    const file: MemoryFileInfo = {
+      path: "/home/naomi/.claude/projects/foo/memory/patterns.md",
+      heading: null,
+    };
+    expect(getDisplayName(file)).toBe("patterns.md");
+  });
+
+  it("returns the heading even when it matches the filename", () => {
+    const file: MemoryFileInfo = {
+      path: "/home/naomi/.claude/projects/foo/memory/MEMORY.md",
+      heading: "MEMORY",
+    };
+    expect(getDisplayName(file)).toBe("MEMORY");
+  });
+
+  it("returns a multi-word heading verbatim", () => {
+    const file: MemoryFileInfo = {
+      path: "/some/path/foo.md",
+      heading: "My Detailed Debugging Notes",
+    };
+    expect(getDisplayName(file)).toBe("My Detailed Debugging Notes");
+  });
+
+  it("falls back gracefully when path has no directory separators", () => {
+    const file: MemoryFileInfo = {
+      path: "lonely-file.md",
+      heading: null,
+    };
+    expect(getDisplayName(file)).toBe("lonely-file.md");
+  });
+});