feat: Implement phases 6 to 9 of the review cycle fix process, including discovery, batching, parallel planning, execution, and completion

- Added Phase 6: Fix Discovery & Batching with intelligent grouping and batching of findings.
- Added Phase 7: Fix Parallel Planning to launch planning agents for concurrent analysis and aggregation of partial plans.
- Added Phase 8: Fix Execution for stage-based execution of fixes with conservative test verification.
- Added Phase 9: Fix Completion to aggregate results, generate summary reports, and handle session completion.
- Introduced new frontend components: ResizeHandle for draggable resizing of sidebar panels and useResizablePanel hook for managing panel sizes with localStorage persistence.
- Added PowerShell script for checking TypeScript errors in source code, excluding test files.

ccw/frontend/_check.ps1

@@ -0,0 +1,13 @@
+Set-Location 'D:\Claude_dms3\ccw\frontend'
+$output = npx tsc --noEmit 2>&1
+$errors = $output | Select-String 'error TS'
+
+# Real errors only
+$real = $errors | Where-Object { $_.Line -notmatch 'TS6133' -and $_.Line -notmatch 'TS1149' -and $_.Line -notmatch 'TS6196' -and $_.Line -notmatch 'TS6192' }
+
+# Source code errors (non-test)
+$src = $real | Where-Object { $_.Line -notmatch '\.test\.' -and $_.Line -notmatch '__tests__' }
+Write-Host "=== SOURCE CODE ERRORS (non-test) ==="
+Write-Host "Count: $($src.Count)"
+Write-Host ""
+foreach ($e in $src) { Write-Host $e.Line }