feat: another wave of features (#61)

## Explanation

This PR bundles several user-facing improvements and feature additions for the v0.3.0 release, including quality-of-life improvements to the UI, new slash commands, better state persistence, and auto-update checking.

## Included Changes

- **Resizable chat input** with drag handle (#58 partial)
- **Arrow key navigation fix** - cursor keys now navigate text when user has typed input (#58)
- **Scroll position persistence** per conversation tab
- **/skill command** for invoking Claude Code skills (#57)
- **Stats persistence fix** - stats now persist across session changes, only reset on disconnect (#59)
- **Auto-update checker** on startup (#17)
- **Resizable character panel** with full-height sprites (#10)
- **Font size and zoom settings** with keyboard shortcuts (Ctrl++/Ctrl+-/Ctrl+0) (#19)

## Closes

Closes #10, #17, #19, #57, #58, #59

## Attestations

- [x] I have read and agree to the Code of Conduct
- [x] I have read and agree to the Community Guidelines
- [x] My contribution complies with the Contributor Covenant
- [x] I have run the linter and resolved any errors
- [x] My pull request uses an appropriate title, matching the conventional commit standards
- [x] My scope of feat/fix/chore/etc. correctly matches the nature of changes in my pull request
- [x] All new and existing tests pass locally with my changes
- [x] Code coverage remains at or above the configured threshold

## Documentation

N/A - Internal app features

## Versioning

Minor - My pull request introduces new non-breaking features.

---
✨ This PR was created with help from Hikari~ 🌸

Co-authored-by: Hikari <hikari@nhcarrigan.com>
Reviewed-on: #61
Co-authored-by: Naomi Carrigan <commits@nhcarrigan.com>
Co-committed-by: Naomi Carrigan <commits@nhcarrigan.com>

src/lib/components/Terminal.svelte

@@ -1,6 +1,6 @@
 <script lang="ts">
   import { claudeStore, type TerminalLine } from "$lib/stores/claude";
-  import { afterUpdate } from "svelte";
+  import { afterUpdate, tick } from "svelte";
   import ConversationTabs from "./ConversationTabs.svelte";
   import Markdown from "./Markdown.svelte";
   import HighlightedText from "./HighlightedText.svelte";
@@ -10,6 +10,8 @@
   let shouldAutoScroll = true;
   let lines: TerminalLine[] = [];
   let currentSearchQuery = "";
+  let currentConversationId: string | null = null;
+  let isRestoringScroll = false;
 
   searchQuery.subscribe((value) => {
     currentSearchQuery = value;
@@ -19,14 +21,46 @@
     lines = value;
   });
 
+  claudeStore.activeConversationId.subscribe(async (newId) => {
+    if (!newId) return;
+
+    // Save current conversation's scroll position before switching
+    if (currentConversationId && currentConversationId !== newId && terminalElement) {
+      const position = shouldAutoScroll ? -1 : terminalElement.scrollTop;
+      claudeStore.saveScrollPosition(currentConversationId, position);
+    }
+
+    currentConversationId = newId;
+
+    // Restore scroll position for the new conversation after DOM updates
+    await tick();
+    if (terminalElement) {
+      const savedPosition = claudeStore.getScrollPosition(newId);
+      isRestoringScroll = true;
+      if (savedPosition === -1) {
+        // Auto-scroll to bottom
+        shouldAutoScroll = true;
+        terminalElement.scrollTop = terminalElement.scrollHeight;
+      } else {
+        // Restore to saved position
+        shouldAutoScroll = false;
+        terminalElement.scrollTop = savedPosition;
+      }
+      // Small delay to prevent the scroll handler from overriding our restore
+      setTimeout(() => {
+        isRestoringScroll = false;
+      }, 50);
+    }
+  });
+
   function handleScroll() {
-    if (!terminalElement) return;
+    if (!terminalElement || isRestoringScroll) return;
     const { scrollTop, scrollHeight, clientHeight } = terminalElement;
     shouldAutoScroll = scrollHeight - scrollTop - clientHeight < 100;
   }
 
   afterUpdate(() => {
-    if (shouldAutoScroll && terminalElement) {
+    if (shouldAutoScroll && terminalElement && !isRestoringScroll) {
       terminalElement.scrollTop = terminalElement.scrollHeight;
     }
   });
@@ -109,7 +143,8 @@
   <div
     bind:this={terminalElement}
     onscroll={handleScroll}
-    class="terminal-content h-[calc(100%-76px)] overflow-y-auto p-4 font-mono text-sm"
+    class="terminal-content h-[calc(100%-76px)] overflow-y-auto p-4 font-mono"
+    style="font-size: var(--terminal-font-size, 14px);"
   >
     {#if lines.length === 0}
       <div class="terminal-waiting italic">