feat: add Ollama icon and modern chat UI styling

- src/chat-view.ts: Add getIcon() returning 'bot' for the view tab icon.
  Improve render() with role-specific CSS classes (user vs assistant) and
  message header structure for better styling hooks.

- src/main.ts: Add ribbon icon ('bot') in the left sidebar that opens the
  chat view with a single click.

- styles.css (new): Modern chat UI with message bubbles, distinct user and
  assistant themes using Obsidian CSS variables, sticky input bar, styled
  send button with accent color, and emoji role indicators.

- install.sh: Copy styles.css into the plugin directory and verify its
  presence during installation.

- README.md: Include styles.css in manual install instructions.

- __mocks__/obsidian.ts: Add addRibbonIcon() mock for test compatibility.

- tests/chat-view.test.ts: Add getIcon() assertion.

src/chat-view.ts

@@ -76,6 +76,10 @@ export class ChatView extends ItemView {
     return 'Ollama Chat';
   }
 
+  getIcon(): string {
+    return 'bot';
+  }
+
   async onOpen(): Promise<void> {
     try {
       await this.ollamaClient.initializeCache();
@@ -145,9 +149,14 @@ export class ChatView extends ItemView {
           contentEl.textContent = msg.content;
         }
       } else {
-        const messageEl = container.createEl('div', { cls: 'ollama-message' });
+        const messageEl = container.createEl('div', {
+          cls: `ollama-message ollama-message-${msg.role}`,
+        });
         messageEl.setAttribute('data-msg-id', msg.id);
-        messageEl.createEl('div', { cls: 'ollama-message-role', text: msg.role });
+
+        const headerEl = messageEl.createEl('div', { cls: 'ollama-message-header' });
+        headerEl.createEl('span', { cls: 'ollama-message-role', text: msg.role });
+
         const contentEl = messageEl.createEl('div', { cls: 'ollama-message-content' });
         contentEl.textContent = msg.content;
       }
@@ -366,15 +375,15 @@ export class ChatView extends ItemView {
   ): Promise<void> {
     const toolResults = (
       await Promise.all(
-      toolCalls.slice(0, MAX_TOOL_CALLS).map(async (toolCall) => {
-        try {
-          const toolResult = await this.toolExecutor.handleToolCall(toolCall);
-          return { ...toolResult, id: toolCall.id };
-        } catch (error) {
-          ErrorHandler.handleError(error, 'ChatView.handleUserInput');
-          return null;
-        }
-      })
+        toolCalls.slice(0, MAX_TOOL_CALLS).map(async (toolCall) => {
+          try {
+            const toolResult = await this.toolExecutor.handleToolCall(toolCall);
+            return { ...toolResult, id: toolCall.id };
+          } catch (error) {
+            ErrorHandler.handleError(error, 'ChatView.handleUserInput');
+            return null;
+          }
+        })
       )
     ).filter((result): result is NonNullable<typeof result> => result !== null);
 
@@ -449,7 +458,10 @@ export class ChatView extends ItemView {
     }
 
     try {
-      const entries = await this.vaultIndexer.searchVault(userMessage, this.settings.vaultSearchLimit);
+      const entries = await this.vaultIndexer.searchVault(
+        userMessage,
+        this.settings.vaultSearchLimit
+      );
       const context = entries
         .map((entry) => `${entry.title}\n${entry.content}`)
         .join('\n\n')
@@ -459,7 +471,8 @@ export class ChatView extends ItemView {
         : userMessage;
 
       // Get the complete messages array for the LLM with all context layers
-      const completeMessages = this.conversationStateManager.getCompleteMessages(userMessageWithContext);
+      const completeMessages =
+        this.conversationStateManager.getCompleteMessages(userMessageWithContext);
 
       const stream = this.ollamaClient.streamChat(completeMessages, tools);