revert: remove codebase intelligence system

Rolled back the intel system due to overengineering concerns:
- 1200+ line hook with SQLite graph database
- 21MB sql.js dependency
- Entity generation spawning additional Claude calls
- Complex system with unclear value

Removed:
- /gsd:analyze-codebase command
- /gsd:query-intel command
- gsd-intel-index.js, gsd-intel-session.js, gsd-intel-prune.js hooks
- gsd-entity-generator, gsd-indexer agents
- entity.md template
- sql.js dependency

Preserved:
- Model profiles feature
- Statusline hook
- All other v1.9.x improvements

-3,065 lines removed

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

commands/gsd/plan-phase.md

@@ -249,9 +249,6 @@ RESEARCH_CONTENT=$(cat "${PHASE_DIR}"/*-RESEARCH.md 2>/dev/null)
 # Gap closure files (only if --gaps mode)
 VERIFICATION_CONTENT=$(cat "${PHASE_DIR}"/*-VERIFICATION.md 2>/dev/null)
 UAT_CONTENT=$(cat "${PHASE_DIR}"/*-UAT.md 2>/dev/null)
-
-# Codebase intelligence (if exists)
-INTEL_CONTENT=$(cat .planning/intel/summary.md 2>/dev/null)
 ```
 
 ## 8. Spawn gsd-planner Agent
@@ -292,11 +289,6 @@ Fill prompt with inlined content and spawn:
 {verification_content}
 {uat_content}
 
-**Codebase Intel (if exists):**
-<codebase-intel>
-{intel_content}
-</codebase-intel>
-
 </planning_context>
 
 <downstream_consumer>