tools: add scope column for capability model

Add a 'scope' TEXT column (default 'homelab') to the tools table so tools
can be namespaced by scope (e.g. "homelab:restart", "datacenter:reboot").
Backward-compat: bare name defaults to "homelab" scope.

Changes:
- Migration #1: ALTER TABLE tools ADD COLUMN scope
- store.Tool: add Scope field, update all SQL and scanTool()
- ipc.Tool DTO and request types: add Scope field
- CoreAPI interface: pass scope in ProposeTool/EnableTool
- storeAPI adapters: forward scope
- cmd/mavend/voice: pass scope (empty → homelab)
- cmd/mavweb/tools: show scope column in UI tables, hidden fields
- All tests updated for scope field
- Migration test made dynamic (startVer = len(migrations))

internal/tool/tool.go

@@ -39,7 +39,7 @@ import (
 type API interface {
 	LookupTool(ctx context.Context, name string) (ipc.Tool, error)
 	ListTools(ctx context.Context, status string) ([]ipc.Tool, error)
-	ProposeTool(ctx context.Context, name, utterance string, ts time.Time) (bool, error)
+	ProposeTool(ctx context.Context, name, utterance, scope string, ts time.Time) (bool, error)
 }
 
 var (