fix: remove chat command and add CI coverage gate (#81)

The chat command advertised three conflicting default models (kimi-k2.6
in help text, openai/gpt-oss in the option builder, google/gemma-3-27b-it
in the service) and was effectively untested (1.21% line coverage).
Remove the command entirely per product direction.

Removed:
- src/commands/chat.ts, src/services/chat-service.ts (+ their tests)
- src/utils/markdown-renderer.ts (only used by chat)
- marked, marked-terminal runtime deps + @types/* dev deps (orphaned)
- CHAT entries from command-structure constants
- Chat Command section from README

Kept DefaultApiKeyManager: still used by auth/credentials/api-key.ts and
the api-keys set-default/get-default subcommands.

Add a CI coverage gate to prevent silent coverage regressions:
- vitest.config.ts: v8 coverage, include all src, exclude generated types/
  schemas/__tests__, thresholds ratcheted just below the post-removal
  baseline (50/52/48/50 stmt/branch/func/line)
- package.json: test:coverage script
- test.yml: run npm run test:coverage in CI (replaces plain test:run)
- .gitignore: ignore coverage/ (artifacts were previously committed)

Author: marcusolsson

.github/workflows/test.yml

@@ -37,8 +37,8 @@ jobs:
       - name: Check formatting with Prettier
         run: npm run format:check
 
-      - name: Run tests
-        run: npm run test:run
+      - name: Run tests with coverage
+        run: npm run test:coverage
 
       - name: Build project
         run: npm run build

.gitignore

@@ -1,5 +1,6 @@
 node_modules
 dist
+coverage
 env
 .aider*
 .env

README.md

@@ -25,24 +25,6 @@ npx berget api-keys create --name "My CLI Key"
 export BERGET_API_KEY=sk_ber_your_api_key_here
 ```
 
-## Chat Command
-
-### Basic Usage
-
-```bash
-# Interactive chat session
-npx berget chat run
-
-# Use specific model
-npx berget chat run openai/gpt-oss
-
-# Send direct message
-npx berget chat run openai/gpt-oss "Explain what Docker is"
-
-# Use pipe for input
-echo "What is Kubernetes?" | npx berget chat run openai/gpt-oss
-```
-
 ## Environment Variables
 
 ```bash
@@ -68,14 +50,11 @@ npx berget --help
 
 ```bash
 # Enable debug mode
-npx berget --debug chat run openai/gpt-oss "test"
+npx berget --debug auth whoami
 
 # Check authentication
 npx berget auth whoami
 
-# List available models
-npx berget chat list
-
 # Check API key status
 npx berget api-keys list
 ```