fix: remove non-existent single-tag API endpoint causing 405 errors

The Toggl v9 API doesn't support GET /workspaces/{wid}/tags/{tagId}.
CacheManager.getTag() now uses getTags() to bulk-fetch and cache all
tags for the workspace, eliminating repeated 405 failures during
time entry hydration.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: madisonrickert

src/cache-manager.ts

@@ -237,19 +237,12 @@ export class CacheManager {
   async getTag(id: number, workspaceId: number): Promise<Tag | null> {
     const cached = this.getCached(this.tags, id);
     if (cached) return cached;
-    
+
     if (!this.api) return null;
-    
-    try {
-      const tag = await this.api.getTag(workspaceId, id);
-      if (tag) {
-        this.setCached(this.tags, id, tag);
-      }
-      return tag;
-    } catch (error) {
-      console.error(`Failed to fetch tag ${id}:`, error);
-      return null;
-    }
+
+    // Fetch all tags for the workspace (populates cache) and find by ID
+    const tags = await this.getTags(workspaceId);
+    return tags.find(t => t.id === id) || null;
   }
 
   async getTags(workspaceId: number): Promise<Tag[]> {

src/toggl-api.ts

@@ -154,10 +154,6 @@ export class TogglAPI {
     return this.request<Tag[]>('GET', `/workspaces/${workspaceId}/tags`);
   }
 
-  async getTag(workspaceId: number, tagId: number): Promise<Tag> {
-    return this.request<Tag>('GET', `/workspaces/${workspaceId}/tags/${tagId}`);
-  }
-
   async createTag(workspaceId: number, name: string): Promise<Tag> {
     return this.request<Tag>('POST', `/workspaces/${workspaceId}/tags`, { name });
   }