test: integration tests with fixture vault

Add 8 integration tests (all #[ignore]) that exercise the full
index-search pipeline using lower-level APIs with isolated temp
directories. Create lib.rs to expose modules for integration test
access. Fixture vault includes 4 notes + excluded .obsidian dir.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: devwhodevs

src/lib.rs

@@ -0,0 +1,7 @@
+pub mod chunker;
+pub mod config;
+pub mod embedder;
+pub mod hnsw;
+pub mod indexer;
+pub mod search;
+pub mod store;

src/main.rs

@@ -1,10 +1,7 @@
-mod chunker;
-mod config;
-mod embedder;
-mod hnsw;
-mod indexer;
-mod search;
-mod store;
+use engraph::config;
+use engraph::indexer;
+use engraph::search;
+use engraph::store;
 
 use anyhow::Result;
 use clap::{Parser, Subcommand};

tests/fixtures/.obsidian/config.md

@@ -0,0 +1,2 @@
+# Obsidian Config
+This should be excluded from indexing.

tests/fixtures/note1.md

@@ -0,0 +1,13 @@
+---
+tags: [rust, programming]
+---
+
+# Rust Error Handling
+
+## Using Result
+
+The Result type is Rust's primary error handling mechanism.
+
+## Using thiserror
+
+The thiserror crate provides derive macros for custom error types.

tests/fixtures/note2.md

@@ -0,0 +1,13 @@
+---
+tags: [python, scripting]
+---
+
+# Python Basics
+
+## Variables
+
+Python uses dynamic typing for variables.
+
+## Functions
+
+Functions are defined with the def keyword.

tests/fixtures/note3.md

@@ -0,0 +1,3 @@
+# Quick Notes
+
+Just a plain note without frontmatter or sections. Contains some text about machine learning and neural networks.

tests/fixtures/subfolder/note4.md

@@ -0,0 +1,9 @@
+---
+tags: [devops]
+---
+
+# Docker Guide
+
+## Building Images
+
+Use Dockerfile to define container images.