feat: justfile task runner and updated install/setup documentation

justfile with build/install/uninstall/test targets. CLAUDE.md updated with
new install path and commands. status-line-setup.md updated for
%LOCALAPPDATA%\ctask\bin location.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

justfile

@@ -0,0 +1,23 @@
+# ctask developer task runner
+# Requires: Go 1.26+, PowerShell 7+ (for install/uninstall)
+# Install just: winget install Casey.Just
+
+# Default: show available targets
+default:
+    @just --list
+
+# Compile ctask from the local repo
+build:
+    go build -o ctask.exe .
+
+# Run the full test suite
+test:
+    go test ./... -v -count=1
+
+# Install ctask to %LOCALAPPDATA%\ctask\bin (Windows, PowerShell)
+install:
+    powershell -NoProfile -ExecutionPolicy Bypass -File scripts/install.ps1
+
+# Uninstall ctask from %LOCALAPPDATA%\ctask\bin (Windows, PowerShell)
+uninstall:
+    powershell -NoProfile -ExecutionPolicy Bypass -File scripts/uninstall.ps1