Add Batch Upgrade Operations and Fix Reconciler/Orphan Handling Bugs

[haochenhu233]

This PR introduces batch upgrade capabilities for service instances and fixes critical bugs in the reconciler's orphan detection logic.

New Features

Batch Service Upgrades

• Upgrade existing services: Operators can now upgrade service instances to newer stemcells directly from the Web UI
• Stemcell filtering by CPI: Only shows stemcells matching the correct Cloud Provider Interface (e.g., *.bosh suffix), avoiding duplicates from legacy CPIs
• Separate BatchDirector connection pool: Dedicated BOSH connection pool for batch operations to avoid impacting normal broker operations
• Stemcell information display: Batch Operation tab now shows current stemcell info for each service instance

VM Monitor Enhancements

• VM monitor status endpoint: New /b/vm-monitor-status endpoint for debugging VM health tracking
• Stemcell info fallback: VM monitor provides stemcell information when manifest data is unavailable

Bug Fixes

Reconciler & Orphan Handling (Critical)

• Fixed vicious cycle bug: Services marked orphaned for >24 hours were incorrectly treated as "deleted", causing FilterServiceDeployments() to skip their existing BOSH deployments permanently. They could never be un-orphaned.
• Fixed empty scan marking all as orphaned: When GetDeployments() failed or returned empty (BOSH temporarily unavailable), ALL services were incorrectly marked as orphaned.
• Added un-orphan logic: Services are now un-orphaned when their BOSH deployment is found in subsequent scans.
• Added orphan timer reset on startup: Each Blacksmith redeploy resets orphan timers, giving operators 24 hours to investigate before cleanup.

Web UI Fixes

• Fixed display for new/deleted services: Corrected rendering issues for services in transitional states
• Fixed manifest display: Resolved bug where manifest data wasn't displaying correctly
• Fixed timestamp display: Service instance timestamps now display correctly

Files Changed

• pkg/reconciler/reconciler.go - Orphan detection fixes, startup timer reset
• pkg/reconciler/synchronizer.go - Un-orphan logic, validation against BOSH deployments
• internal/handlers/bosh/handler.go - VM monitor status endpoint, stemcell filtering
• internal/bosh/director.go - Batch director pool
• ui/* - Web UI enhancements for batch operations

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[krutten]

Additional functionality looks good. Addition to Mocks present and abstraction seems clean. LGTM