feat: add configuration loading and logging setup

[durgeshninave9]

• Implemented configuration loading with default values and environment variable overrides in shared/config/config_test.go.
• Added PostgreSQL client implementation in shared/db/postgres/postgres.go with connection pooling and schema initialization.
• Created structured logger setup in shared/logger/logger.go with configurable log level and format.
• Added tests for logger setup in shared/logger/logger_test.go.
• Introduced gRPC plugin structure for language parsing in shared/protocol/v1/plugin/placeholder.go.
• Defined Universal Code Model (UCM) structures in shared/protocol/v1/ucm/placeholder.go.
• Implemented OpenTelemetry tracing setup in shared/tracer/tracer.go for distributed tracing.
• Updated Go module dependencies in shared/go.mod and shared/go.sum.