feat: default list_alerts to active alerts only

Change list_alerts (MCP tool) and alerts (CLI command) to show only
active (non-silenced, non-inhibited) alerts by default. Add state=all
option and --all CLI flag to show all alerts when needed.

- MCP: list_alerts with no state param now returns active alerts only
- MCP: list_alerts with state=all returns all alerts (previous default)
- CLI: alerts command defaults to active, --all shows everything
- Add tests for new default behavior and state=all option
- Update README with new CLI examples
- Bump version to 0.3.0
- Clarify version bumping rules in CLAUDE.md

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

README.md

@@ -244,9 +244,10 @@ hm-options get programs.git.enable
 **Lab Monitoring CLI:**
 
 ```bash
-# List alerts
+# List alerts (defaults to active only)
 lab-monitoring alerts
-lab-monitoring alerts --state active
+lab-monitoring alerts --all           # Include silenced/inhibited alerts
+lab-monitoring alerts --state all     # Same as --all
 lab-monitoring alerts --severity critical
 
 # Execute PromQL queries
@@ -341,7 +342,7 @@ hm-options -d "sqlite://my.db" index hm-unstable
 
 | Tool | Description |
 |------|-------------|
-| `list_alerts` | List alerts with optional filters (state, severity, receiver) |
+| `list_alerts` | List alerts with optional filters (state, severity, receiver). Defaults to active alerts only; use state=all to include silenced/inhibited |
 | `get_alert` | Get full details for a specific alert by fingerprint |
 | `search_metrics` | Search metric names with substring filter, enriched with metadata |
 | `get_metric_metadata` | Get type, help text, and unit for a specific metric |