refactor(coder-labs/gemini): support terraform provider coder v2.12.0 (#493)

## Description

Updates the module to use the new version of the agentapi module for
Coder 2.28

## Type of Change

- [ ] New module
- [ ] New template
- [ ] Bug fix
- [x] Feature/enhancement
- [ ] Documentation
- [ ] Other

## Module Information

**Path:** `registry/[namespace]/modules/[module-name]`  
**New version:** `v3.0.0`  
**Breaking change:** [x] Yes [ ] No

## Testing & Validation

- [x] Tests pass (`bun test`)
- [x] Code formatted (`bun fmt`)
- [ ] Changes tested locally

## Related Issues

- https://github.com/coder/internal/issues/1065

## Related PRs

- https://github.com/coder/registry/pull/485

---------

Co-authored-by: DevCats <christofer@coder.com>

registry/coder-labs/modules/gemini/README.md

@@ -13,7 +13,7 @@ Run [Gemini CLI](https://github.com/google-gemini/gemini-cli) in your workspace
 ```tf
 module "gemini" {
   source   = "registry.coder.com/coder-labs/gemini/coder"
-  version  = "2.1.2"
+  version  = "3.0.0"
   agent_id = coder_agent.main.id
   folder   = "/home/coder/project"
 }
@@ -46,7 +46,7 @@ variable "gemini_api_key" {
 
 module "gemini" {
   source         = "registry.coder.com/coder-labs/gemini/coder"
-  version        = "2.1.2"
+  version        = "3.0.0"
   agent_id       = coder_agent.main.id
   gemini_api_key = var.gemini_api_key
   folder         = "/home/coder/project"
@@ -94,7 +94,7 @@ data "coder_parameter" "ai_prompt" {
 module "gemini" {
   count                = data.coder_workspace.me.start_count
   source               = "registry.coder.com/coder-labs/gemini/coder"
-  version              = "2.1.2"
+  version              = "3.0.0"
   agent_id             = coder_agent.main.id
   gemini_api_key       = var.gemini_api_key
   gemini_model         = "gemini-2.5-flash"
@@ -118,7 +118,7 @@ For enterprise users who prefer Google's Vertex AI platform:
 ```tf
 module "gemini" {
   source         = "registry.coder.com/coder-labs/gemini/coder"
-  version        = "2.1.2"
+  version        = "3.0.0"
   agent_id       = coder_agent.main.id
   gemini_api_key = var.gemini_api_key
   folder         = "/home/coder/project"

registry/coder-labs/modules/gemini/main.tf

@@ -4,7 +4,7 @@ terraform {
   required_providers {
     coder = {
       source  = "coder/coder"
-      version = ">= 2.7"
+      version = ">= 2.12"
     }
   }
 }
@@ -177,7 +177,7 @@ EOT
 
 module "agentapi" {
   source  = "registry.coder.com/coder/agentapi/coder"
-  version = "1.2.0"
+  version = "2.0.0"
 
   agent_id             = var.agent_id
   folder               = local.folder
@@ -225,4 +225,8 @@ module "agentapi" {
      GEMINI_TASK_PROMPT='${var.task_prompt}' \
      /tmp/start.sh
    EOT
-}
+}
+
+output "task_app_id" {
+  value = module.agentapi.task_app_id
+}