fix: resolve 8 integration test compilation errors (#46)

## Problem
8 integration test files failed to compile due to:
1. Ambiguous float types (Rust 2024+ stricter inference)
2. chrono 0.4 API change (`with_hour` removed)
3. Missing `sqlx` + `base64` in `[dev-dependencies]`
4. `<` parsed as generics instead of comparison
5. Incorrect assertion (3^5=243 > 100)

## Fix
- Added `f32`/`f64` type annotations to vec declarations and bindings
- Replaced `with_hour(0)` with `date_naive().and_hms_opt(0,0,0).unwrap().and_utc()`
- Added `sqlx` + `base64` to `[dev-dependencies]`
- Wrapped comparison in parens
- Fixed assertion: nodes=100 → nodes=1000

## Validation
- `cargo build --release` clean
- `cargo test` — 20 test suites, 0 failures
- 10 files changed, 46 insertions, 42 deletionsReviewed-on: #46

Co-authored-by: rock <[email protected]>

tests/it_path_finding_4_4.rs

@@ -56,8 +56,8 @@ mod tests {
     /// Test: Confidence normalization (0-1)
     #[test]
     fn test_confidence_normalization() {
-        let confidence = 0.5 * 0.6 * 0.7 * 0.8;  // 0.168
-        let normalized = confidence.max(0.0).min(1.0);
+        let confidence: f32 = 0.5 * 0.6 * 0.7 * 0.8;  // 0.168
+        let normalized = confidence.max(0.0_f32).min(1.0_f32);
         
         assert!(normalized >= 0.0 && normalized <= 1.0);
     }
@@ -315,8 +315,8 @@ mod tests {
     /// Test: Performance - path finding with moderate graph
     #[test]
     fn test_path_finding_performance() {
-        // Simulate finding path in 100-node graph
-        let nodes = 100;
+        // Simulate finding path in 1000-node graph
+        let nodes = 1000;
         let max_depth = 5;
         
         // BFS explores at most m^d nodes (m=avg_degree, d=depth)