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_query_reasoning_5_3.rs

@@ -342,11 +342,11 @@ mod tests {
     /// Test: Answer confidence averaging
     #[test]
     fn test_confidence_averaging() {
-        let conf1 = 0.9;
+        let conf1: f64 = 0.9;
         let conf2 = 0.8;
         let avg = (conf1 + conf2) / 2.0;
         
-        assert!((avg - 0.85).abs() < 0.01);
+        assert!((avg - 0.85_f64).abs() < 0.01);
     }
 
     /// Test: Answer deduplication