Remove custom providers from settings (#1951)

* feat(providers): remove custom providers from settings

Add a destructive removal flow so mistaken custom providers can be deleted from config.json instead of only disabled.

* test(app): cover provider removal with e2e

Move provider removal coverage out of mocked component tests and into the real Settings flow.

* fix(providers): keep removal live after config updates

packages/protocol/src/messages.ts

@@ -163,6 +163,7 @@ export const MutableDaemonConfigPatchSchema = z
     providers: z
       .record(z.string(), MutableDaemonProviderConfigSchema.partial().passthrough())
       .optional(),
+    removeProviders: z.array(z.string().min(1)).optional(),
     metadataGeneration: MutableMetadataGenerationConfigSchema.partial().optional(),
     autoArchiveAfterMerge: z.boolean().optional(),
     enableTerminalAgentHooks: z.boolean().optional(),
@@ -263,6 +264,7 @@ export const ProviderSnapshotEntrySchema = z.object({
   provider: AgentProviderSchema,
   status: ProviderStatusSchema,
   enabled: z.boolean().optional().default(true),
+  source: z.enum(["builtin", "custom"]).optional(),
   error: z.string().optional(),
   models: z.array(AgentModelDefinitionSchema).optional(),
   modes: z.array(AgentModeSchema).optional(),
@@ -2471,6 +2473,8 @@ export const ServerInfoStatusPayloadSchema = z
         workspaceGithubRepositorySearch: z.boolean().optional(),
         // COMPAT(projectCreateDirectory): added in v0.1.108, remove gate after 2027-01-15.
         projectCreateDirectory: z.boolean().optional(),
+        // COMPAT(providerRemoval): added in v0.1.105, drop the gate when floor >= v0.1.105.
+        providerRemoval: z.boolean().optional(),
       })
       .optional(),
   })