feat(doctor): add Dolt-specific diagnostics and performance profiling

[groblegark]

Summary

Add comprehensive diagnostic and performance profiling tools for the Dolt storage backend. This complements the recently merged test suite (#1299) and documentation (#1310).

New Files

cmd/bd/doctor/dolt.go (347 lines)

Adds Dolt-specific health checks to bd doctor:

Check	Purpose
CheckDoltConnection	Verify database connectivity
CheckDoltSchema	Validate schema integrity
CheckDoltSync	Check sync status with remotes
CheckDoltLock	Detect stale lock files
CheckDoltServerMode	Verify server mode configuration

cmd/bd/doctor/perf_dolt.go (506 lines)

Adds Dolt-specific performance diagnostics:

Feature	Description
Connection timing	Time to establish database connection
Query benchmarks	List, show, filter operation timing
Complex queries	Timing for joins and aggregations
Commit log queries	dolt_log performance
Database statistics	Issue counts, dependencies
CPU profiling	Optional pprof profile generation

cmd/bd/doctor/types.go

• Adds CategoryPerformance for grouping performance checks

Usage

# Run standard diagnostics (includes Dolt checks when applicable)
bd doctor

# Run Dolt-specific performance diagnostics
bd doctor perf --dolt

# Run with CPU profiling
bd doctor perf --dolt --profile

Example Output

=== Dolt Performance Diagnostics ===

Backend: dolt-embedded
Server Mode: false
Platform: linux/amd64
Go Version: go1.21.5
Database Size: 2.4 MB

Issues: 1,234 total (890 open, 344 closed)
Dependencies: 456

Timing (ms):
  Connection:     523
  Ready work:     45
  List open:      89
  Show issue:     12
  Complex query:  234
  Commit log:     167

Testing

All diagnostics are designed to:

• Skip gracefully if Dolt backend isn't configured
• Handle both embedded and server modes
• Provide actionable error messages with fix suggestions

Related

• test(dolt): add comprehensive test suite for Dolt storage backend #1299: Dolt test suite (merged)
• docs: add comprehensive Dolt backend guide #1310: Dolt documentation (pending)

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