Implement the first three built-in context strategies for the ACMS v1
context assembly pipeline:
1. SimpleKeywordStrategy (quality 0.3) - Keyword matching on fragment
content with word-density fallback. Universal fallback strategy.
2. SemanticEmbeddingStrategy (quality 0.6) - Jaccard word-overlap
similarity scoring between query and fragment content.
3. BreadthDepthNavigatorStrategy (quality 0.85) - UKO node hierarchy
navigation prioritising fragments near focus nodes with higher
detail depths. Primary strategy for code projects.
All strategies implement the v1 ContextStrategy Protocol from
acms_service.py and can be registered with ACMSPipeline via
register_strategy().
Includes:
- 28 Behave BDD scenarios covering ranking, budget, capabilities,
can_handle confidence, explain, empty input, and pipeline
registration
- 9 Robot Framework integration tests
- ASV benchmarks at 10/100/1000 fragment scales for all 3 strategies
- Vulture whitelist entries for public API symbols
- 100% coverage on context_strategies.py
ISSUES CLOSED: #541
