Enhance bd doctor with bd prime migration recommendations (bd-0fvq)

Add comprehensive detection and migration guidance for old beads integration
patterns. This helps users adopt the more efficient bd prime approach.

Changes:
- Enhanced CheckLegacyBeadsSlashCommands with detailed migration steps
  and token efficiency benefits (99% reduction: ~10.5k → ~50 tokens)
- Added CheckAgentDocumentation to detect missing AGENTS.md/CLAUDE.md
  and suggest bd onboard or bd setup claude
- Enhanced CheckClaude to recommend bd prime hooks for MCP-only setups
  with clear token efficiency messaging
- Added comprehensive tests for all new checks

bd doctor now detects:
1. Old slash command patterns (/beads:*) and recommends bd prime hooks
2. Missing agent documentation and suggests creating it
3. MCP-only setups without hooks and shows token savings potential
4. Provides clear migration paths and benefits for all scenarios

Token efficiency messaging:
- MCP mode: ~50 tokens vs ~10.5k for full scan (99% reduction)
- CLI mode: ~1-2k tokens with automatic context recovery
- Hooks auto-refresh context on SessionStart and PreCompact

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

cmd/bd/doctor/claude.go

@@ -58,14 +58,34 @@ func CheckClaude() DoctorCheck {
 			Name:    "Claude Integration",
 			Status:  "warning",
 			Message: "MCP server installed but hooks missing",
-			Fix:     "Run: bd setup claude",
+			Detail: "MCP-only mode: relies on tools for every query (~10.5k tokens)\n" +
+				"  bd prime hooks provide much better token efficiency",
+			Fix: "Add bd prime hooks for better token efficiency:\n" +
+				"  1. Run 'bd setup claude' to add SessionStart/PreCompact hooks\n" +
+				"\n" +
+				"Benefits:\n" +
+				"  • MCP mode: ~50 tokens vs ~10.5k for full tool scan (99% reduction)\n" +
+				"  • Automatic context refresh on session start and compaction\n" +
+				"  • Works alongside MCP tools for when you need them\n" +
+				"\n" +
+				"See: bd setup claude --help",
 		}
 	} else {
 		return DoctorCheck{
 			Name:    "Claude Integration",
 			Status:  "warning",
 			Message: "Not configured",
-			Fix:     "Run: bd setup claude (and install beads plugin for slash commands)",
+			Detail: "Claude can use bd more effectively with hooks and optional plugin",
+			Fix: "Set up Claude integration:\n" +
+				"  1. Run 'bd setup claude' to add SessionStart/PreCompact hooks\n" +
+				"  2. (Optional) Install beads plugin for slash commands\n" +
+				"\n" +
+				"Benefits:\n" +
+				"  • Hooks: Auto-inject workflow context (~50-2k tokens)\n" +
+				"  • Plugin: Convenient slash commands + MCP tools\n" +
+				"  • CLI mode: Works without plugin (hooks + manual 'bd prime')\n" +
+				"\n" +
+				"See: bd setup claude --help",
 		}
 	}
 }