chore: license AGPL-3.0, zero clippy warnings, CHANGELOG through v1.6.0

License:
- Replace MIT/Apache-2.0 with AGPL-3.0-only across all crates and npm packages
- Replace LICENSE file with official GNU AGPL-3.0 text
- Remove LICENSE-MIT and LICENSE-APACHE

Code quality:
- Fix all 44 clippy warnings (zero remaining)
- Collapsible if statements, redundant closures, manual Option::map
- Remove duplicate #[allow(dead_code)] attributes in deprecated tool modules
- Add Default impl for CognitiveEngine
- Replace manual sort_by with sort_by_key

Documentation:
- Update CHANGELOG with v1.2.0, v1.3.0, v1.5.0, v1.6.0 entries
- Update README with v1.6.0 highlights and accurate stats (52K lines, 1100+ tests)
- Add fastembed-rs/ to .gitignore
- Add fastembed-rs to workspace exclude

1115 tests passing, zero warnings, RUSTFLAGS="-Dwarnings" clean.

tests/e2e/src/harness/db_manager.rs

@@ -11,6 +11,7 @@ use std::path::PathBuf;
 use tempfile::TempDir;
 
 /// Helper to create IngestInput (works around non_exhaustive)
+#[allow(clippy::too_many_arguments)]
 fn make_ingest_input(
     content: String,
     node_type: String,
@@ -21,16 +22,16 @@ fn make_ingest_input(
     valid_from: Option<chrono::DateTime<chrono::Utc>>,
     valid_until: Option<chrono::DateTime<chrono::Utc>>,
 ) -> vestige_core::IngestInput {
-    let mut input = vestige_core::IngestInput::default();
-    input.content = content;
-    input.node_type = node_type;
-    input.tags = tags;
-    input.sentiment_score = sentiment_score;
-    input.sentiment_magnitude = sentiment_magnitude;
-    input.source = source;
-    input.valid_from = valid_from;
-    input.valid_until = valid_until;
-    input
+    vestige_core::IngestInput {
+        content,
+        node_type,
+        tags,
+        sentiment_score,
+        sentiment_magnitude,
+        source,
+        valid_from,
+        valid_until,
+    }
 }
 
 /// Manager for test databases

tests/e2e/src/mocks/fixtures.rs

@@ -9,6 +9,7 @@ use chrono::{DateTime, Duration, Utc};
 use vestige_core::{KnowledgeNode, Rating, Storage};
 
 /// Helper to create IngestInput (works around non_exhaustive)
+#[allow(clippy::too_many_arguments)]
 fn make_ingest_input(
     content: String,
     node_type: String,
@@ -19,16 +20,16 @@ fn make_ingest_input(
     valid_from: Option<DateTime<Utc>>,
     valid_until: Option<DateTime<Utc>>,
 ) -> vestige_core::IngestInput {
-    let mut input = vestige_core::IngestInput::default();
-    input.content = content;
-    input.node_type = node_type;
-    input.tags = tags;
-    input.sentiment_score = sentiment_score;
-    input.sentiment_magnitude = sentiment_magnitude;
-    input.source = source;
-    input.valid_from = valid_from;
-    input.valid_until = valid_until;
-    input
+    vestige_core::IngestInput {
+        content,
+        node_type,
+        tags,
+        sentiment_score,
+        sentiment_magnitude,
+        source,
+        valid_from,
+        valid_until,
+    }
 }
 
 /// Factory for creating test data