feat: productivity suite — task loop, workflow, theming, docs & more (#197)

## Summary

A large productivity-focused feature branch delivering a suite of improvements across automation, project management, theming, performance, and documentation.

### Features

- **Guided Project Workflow** (#189) — Four-phase workflow panel (Discuss → Plan → Execute → Verify) to keep projects structured from idea to completion
- **Automated Task Loop** (#179) — Per-task conversation orchestration with wave-based parallel execution, blocked-task detection, and concurrency control
- **Wave-Based Parallel Execution** (#191) — Tasks run in dependency-aware waves with configurable concurrency; independent tasks execute in parallel
- **Auto-Commit After Task Completion** (#192) — Task Loop optionally commits after each completed task so progress is never lost
- **PRD Creator** (#180) — AI-assisted PRD and task list panel that outputs `hikari-tasks.json` for the Task Loop to consume
- **Project Context Panel** (#188) — Persistent `PROJECT.md`, `REQUIREMENTS.md`, `ROADMAP.md`, and `STATE.md` files injected into Claude's context automatically
- **Codebase Mapper** (#190) — Generates a `CODEBASE.md` architectural summary so Claude always understands the project structure
- **Community Preset Themes** (#181) — Six built-in community themes: Dracula, Catppuccin Mocha, Nord, Solarized Dark, Gruvbox Dark, and Rosé Pine
- **In-App Changelog Panel** (#193) — Fetches release notes from GitHub at runtime and displays them inside the app
- **Full Embedded Documentation** (#196) — Replaced the single-page help modal with a 12-page paginated docs browser featuring a sidebar TOC, prev/next navigation, keyboard navigation (arrow keys, `?` shortcut), and comprehensive coverage of every feature

### Performance & Fixes

- **Lazy Loading & Virtualisation** (#194) — Virtual windowing for conversation history, markdown memoisation, and debounced search for smooth rendering of large sessions
- **Ctrl+C Copy Fix** (#195) — `Ctrl+C` now copies selected text as expected; interrupt-Claude behaviour only fires when no text is selected

### UX

- Back-to-workflow button in PRD Creator and Task Loop panels for easy navigation
- Navigation icon cluster replaced with a single clean dropdown menu

## Closes

Closes #179
Closes #180
Closes #181
Closes #188
Closes #189
Closes #190
Closes #191
Closes #192
Closes #193
Closes #194
Closes #195
Closes #196

---

✨ This PR was created with help from Hikari~ 🌸

Reviewed-on: #197
Co-authored-by: Hikari <hikari@nhcarrigan.com>
Co-committed-by: Hikari <hikari@nhcarrigan.com>

src/lib/components/Terminal.test.ts

@@ -89,6 +89,27 @@ function truncateToolContent(content: string): string {
   return content.slice(0, TOOL_COLLAPSE_THRESHOLD) + "…";
 }
 
+// Virtual windowing helpers — mirror the logic in Terminal.svelte
+
+const WINDOW_SIZE = 150;
+const LOAD_CHUNK = 50;
+const AVG_LINE_HEIGHT = 60;
+
+/** Returns the windowStart index when auto-scrolling to the bottom. */
+function autoScrollWindowStart(linesLength: number, windowSize: number): number {
+  return Math.max(0, linesLength - windowSize);
+}
+
+/** Returns the new windowStart after loading LOAD_CHUNK older messages. */
+function olderWindowStart(currentStart: number, chunkSize: number): number {
+  return Math.max(0, currentStart - chunkSize);
+}
+
+/** Returns the height in pixels of the invisible top spacer. */
+function topSpacerHeight(windowStart: number, avgLineHeight: number): number {
+  return windowStart * avgLineHeight;
+}
+
 // ---
 
 describe("getLineClass", () => {
@@ -262,3 +283,86 @@ describe("truncateToolContent", () => {
     expect(result.endsWith("...")).toBe(false);
   });
 });
+
+describe("autoScrollWindowStart", () => {
+  it("returns 0 when lines fit within the window", () => {
+    expect(autoScrollWindowStart(50, WINDOW_SIZE)).toBe(0);
+  });
+
+  it("returns 0 when lines exactly fill the window", () => {
+    expect(autoScrollWindowStart(WINDOW_SIZE, WINDOW_SIZE)).toBe(0);
+  });
+
+  it("advances when lines exceed the window size", () => {
+    expect(autoScrollWindowStart(200, WINDOW_SIZE)).toBe(50);
+  });
+
+  it("never returns a negative value", () => {
+    expect(autoScrollWindowStart(0, WINDOW_SIZE)).toBe(0);
+  });
+
+  it("keeps last WINDOW_SIZE lines visible for large collections", () => {
+    expect(autoScrollWindowStart(500, WINDOW_SIZE)).toBe(350);
+  });
+});
+
+describe("olderWindowStart", () => {
+  it("subtracts the chunk size from the current start", () => {
+    expect(olderWindowStart(100, LOAD_CHUNK)).toBe(50);
+  });
+
+  it("never returns a negative value when chunk is larger than start", () => {
+    expect(olderWindowStart(20, LOAD_CHUNK)).toBe(0);
+  });
+
+  it("returns 0 when current start is 0", () => {
+    expect(olderWindowStart(0, LOAD_CHUNK)).toBe(0);
+  });
+
+  it("returns 0 when current start exactly equals the chunk size", () => {
+    expect(olderWindowStart(LOAD_CHUNK, LOAD_CHUNK)).toBe(0);
+  });
+
+  it("correctly loads a partial chunk near the beginning", () => {
+    expect(olderWindowStart(30, LOAD_CHUNK)).toBe(0);
+  });
+});
+
+describe("topSpacerHeight", () => {
+  it("returns 0 when windowStart is 0", () => {
+    expect(topSpacerHeight(0, AVG_LINE_HEIGHT)).toBe(0);
+  });
+
+  it("multiplies windowStart by avgLineHeight", () => {
+    expect(topSpacerHeight(10, AVG_LINE_HEIGHT)).toBe(600);
+  });
+
+  it("scales linearly with windowStart", () => {
+    expect(topSpacerHeight(50, AVG_LINE_HEIGHT)).toBe(3000);
+    expect(topSpacerHeight(100, AVG_LINE_HEIGHT)).toBe(6000);
+    expect(topSpacerHeight(150, AVG_LINE_HEIGHT)).toBe(9000);
+  });
+
+  it("uses the provided avgLineHeight rather than a hard-coded value", () => {
+    expect(topSpacerHeight(5, 100)).toBe(500);
+    expect(topSpacerHeight(5, 80)).toBe(400);
+  });
+});
+
+describe("virtual windowing constants", () => {
+  it("WINDOW_SIZE is 150", () => {
+    expect(WINDOW_SIZE).toBe(150);
+  });
+
+  it("LOAD_CHUNK is 50", () => {
+    expect(LOAD_CHUNK).toBe(50);
+  });
+
+  it("LOAD_CHUNK is smaller than WINDOW_SIZE", () => {
+    expect(LOAD_CHUNK).toBeLessThan(WINDOW_SIZE);
+  });
+
+  it("AVG_LINE_HEIGHT is a positive number", () => {
+    expect(AVG_LINE_HEIGHT).toBeGreaterThan(0);
+  });
+});