fix(lint): correct .golangci.yml for v2 format

Based on official golangci-lint v2 documentation (verified via NIA):
- Added required 'version: 2' declaration
- Changed 'disable-all: true' to 'default: none' (v2 syntax)
- Kept 'linters-settings' and 'issues.exclude-rules' (correct for v2)

Documentation source: https://golangci-lint.run/docs/configuration/file

Fixes: v2 configuration validation error