feat: Replace Gemini SDK with OpenAI-compatible LLM API

- Replaced Google Gemini SDK with generic OpenAI-compatible /v1/chat/completions API (Ktor HTTP)
- Default provider: Groq (free tier) with LLaMA 3 70B model
- Added configurable API endpoint URL in settings
- Supported models: LLaMA 3 70B/8B, Mixtral 8x7B, Gemma 2 9B
- Compatible with Groq, OpenAI, Ollama, LM Studio, any OpenAI-compatible API
- Removed com.google.ai.client.generativeai:generativeai dependency
- Updated UI strings and API key guide

Author: Baker

app/build.gradle.kts

@@ -98,7 +98,6 @@ dependencies {
     ksp(libs.hilt.android.compiler)
     ksp(libs.hilt.compile)
 
-    implementation("com.google.ai.client.generativeai:generativeai:0.9.0")
     implementation("androidx.security:security-crypto:1.1.0")
     implementation("com.udojava:EvalEx:2.7")
     implementation("androidx.activity:activity-compose:1.11.0")

app/src/main/java/com/babelsoftware/airnote/data/repository/AiModels.kt

@@ -3,24 +3,30 @@ package com.babelsoftware.airnote.data.repository
 import androidx.annotation.StringRes
 import com.babelsoftware.airnote.R
 
-data class GeminiModelInfo(
+data class LlmModelInfo(
     val name: String,
     @StringRes val displayNameResId: Int
 )
 
-object GeminiModels {
+object LlmModels {
     val supportedModels = listOf(
-        GeminiModelInfo(
-            name = "gemini-2.5-flash",
-            displayNameResId = R.string.gemini_models_25
+        LlmModelInfo(
+            name = "llama3-70b-8192",
+            displayNameResId = R.string.llm_models_llama3_70b
         ),
-        GeminiModelInfo(
-            name = "gemini-2.0-flash-001",
-            displayNameResId = R.string.gemini_models_20
+        LlmModelInfo(
+            name = "llama3-8b-8192",
+            displayNameResId = R.string.llm_models_llama3_8b
         ),
-        GeminiModelInfo(
-            name = "gemini-1.5-flash-latest",
-            displayNameResId = R.string.gemini_models_15
+        LlmModelInfo(
+            name = "mixtral-8x7b-32768",
+            displayNameResId = R.string.llm_models_mixtral_8x7b
+        ),
+        LlmModelInfo(
+            name = "gemma2-9b-it",
+            displayNameResId = R.string.llm_models_gemma2_9b
         )
     )
-}
+
+    val defaultEndpoint = "https://api.groq.com/openai/v1"
+}