fix(golangci-lint): use /v2 module path for go install per Go conventions

The previous fix prioritized GitHub binary downloads, but the go install
fallback was still using the v1 module path which only has versions up to
v1.64.8.

Go modules v2+ require a /v2 suffix in the module path per semantic import
versioning conventions. golangci-lint v2.5.0 is available in the Go module
proxy at: github.com/golangci/golangci-lint/v2

Changes:
- Updated go install command to use /v2 module path
- Added comment explaining the v2+ Go module convention
- Verified v2.5.0 is available: https://proxy.golang.org/github.com/golangci/golangci-lint/v2/@latest

Result: Both GitHub binary (primary) and go install (fallback) now correctly
install v2.5.0 instead of v1.64.8.

Credit: User pointed out the v2 module path requirement for Go v2+ versions.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: AI Assistant

scripts/install_core.sh

@@ -741,8 +741,9 @@ install_golangci_lint() {
     fi
   fi
   # Fallback to go install (requires go 1.17+)
+  # Note: v2+ uses /v2 module path per Go module conventions
   if command -v go >/dev/null 2>&1; then
-    GO111MODULE=on go install github.com/golangci/golangci-lint/cmd/golangci-lint@latest && $INSTALL "$(go_bin_path)/golangci-lint" "$BIN_DIR/golangci-lint" && return
+    GO111MODULE=on go install github.com/golangci/golangci-lint/v2/cmd/golangci-lint@latest && $INSTALL "$(go_bin_path)/golangci-lint" "$BIN_DIR/golangci-lint" && return
   fi
 }