feat: auto-create search/tts providers at startup with enable toggle

- Add `enable` column (default false) to search_providers and tts_providers tables
- Auto-create default entries for all provider types on startup (disabled by default)
- Add enable/disable Switch toggle in frontend for both search and TTS providers
- Show green status dot in sidebar for enabled providers, sort enabled first
- Filter bot settings dropdowns to only show enabled providers

spec/docs.go

@@ -12206,6 +12206,9 @@ const docTemplate = `{
                 "created_at": {
                     "type": "string"
                 },
+                "enable": {
+                    "type": "boolean"
+                },
                 "id": {
                     "type": "string"
                 },
@@ -12307,6 +12310,9 @@ const docTemplate = `{
                     "type": "object",
                     "additionalProperties": {}
                 },
+                "enable": {
+                    "type": "boolean"
+                },
                 "name": {
                     "type": "string"
                 },
@@ -12624,6 +12630,9 @@ const docTemplate = `{
                 "created_at": {
                     "type": "string"
                 },
+                "enable": {
+                    "type": "boolean"
+                },
                 "id": {
                     "type": "string"
                 },
@@ -12665,6 +12674,9 @@ const docTemplate = `{
         "tts.UpdateProviderRequest": {
             "type": "object",
             "properties": {
+                "enable": {
+                    "type": "boolean"
+                },
                 "name": {
                     "type": "string"
                 }