feat: Phase 1-2 v2 stabilization

[linhdmn]

Summary

Implements Phase 1 (Stabilize Current v2 Core) and Phase 2 (Team Sync Shared Backend MVP) from the LeanKG roadmap.

Phase 1 Changes

Schema migration hardening (src/db/schema.rs)

• Replaces stacked :replace chain (migrations 002-005) with safe ensure_canonical_* functions
• Inspects column count first, only applies :replace on schema mismatch
• Legacy migrations marked as applied to skip old chain
• Adds repair_canonical_schema, get_column_count, ensure_incidents_table

Env-aware indexing (src/cli/mod.rs, src/main.rs, src/mcp/tools.rs, src/mcp/handler.rs)

• --env, --service-name, --version flags on leankg index CLI
• Same params on mcp_index MCP tool

Service metadata model (src/db/models.rs, src/db/schema.rs, src/db/mod.rs)

• ServiceMetadata struct: team, on_call, repo_url, language, health_endpoint, slo_p99_ms, tags, version, deploy_envs
• CozoDB relation with indexes
• upsert_service_metadata and get_service_metadata CRUD

Service context completeness (src/graph/query.rs, src/mcp/handler.rs)

• Extended ServiceContext with: team, on_call, repo_url, language, schemas, last_incident, known_risks
• Schema extraction query and get_service_metadata_fields helper

Incident validation (src/db/mod.rs)

• validate_incident: checks severity (P0-P3), required fields (title, root_cause, resolution, author), valid timestamps, ticket format

Folder-structure graph (src/indexer/mod.rs)

• Directory nodes with contains edges (dir->dir, dir->file)
• Directory metadata: child_count, total_lines, language_distribution

Wake-up context protocol (src/mcp/tools.rs, src/mcp/handler.rs, src/graph/query.rs)

• wake_up MCP tool returning ~170 token project summary
• GraphEngine::wake_up_summary generates L0/L1 context
• Cached in .leankg/wake_up.txt

Phase 2 Changes

v2 REST API (src/api/mod.rs, src/api/handlers.rs)

• /api/v2/status - project status
• /api/v2/service/context - service context
• /api/v2/incidents - incident query
• /api/v2/env/diff - environment diff
• /api/v2/health - health check

Team auth middleware (src/api/auth.rs)

• team_token_middleware with X-LeanKG-Token, X-LeanKG-Engineer, X-LeanKG-Env headers
• TeamAuthContext struct and get_team_ctx extractor

Push/pull CLI (src/cli/mod.rs, src/main.rs, Cargo.toml)

• leankg push - push local graph to remote server
• leankg pull - pull shared graph from remote server
• Uses reqwest blocking client with json support

CI/CD workflow (.github/workflows/leankg-update.yml)

• Auto-index on push to main
• Push to shared server if LEANKG_TOKEN is configured

Verification

• cargo clippy: 0 warnings, 0 errors
• cargo test --lib: 352 passed, 0 failed
• 16 files changed, +948/-84