feat: add structured logging with tracing, JSON format, and file rota…

[Manuelshub]

Closes #38

Summary

Basic println! statements provided no structured output, no log levels, and no way to configure verbosity or format for CI/CD pipelines. This PR introduces a structured logging subsystem using the tracing ecosystem, with support for multiple log levels, human and JSON output formats, and optional file rotation.

Changes

New: src/utils/logging.rs

• LogFormat enum — Human (default) or Json
• LogConfig struct — configures level, format, and optional log directory
• init(config: LogConfig) — initialises the global tracing subscriber; supports all four combinations of format × file/stderr
• config_from_env() — builds LogConfig from CLI flags
• File rotation via tracing-appender::rolling::daily when a log directory is provided
• RUST_LOG environment variable overrides the configured log level

src/main.rs

• Added --log-format <human|json> global CLI flag
• Added --log-dir <path> global CLI flag for file rotation
• logging::init() called at startup before any command runs

Cargo.toml

• Added tracing = "0.1"
• Added tracing-subscriber = { version = "0.3", features = ["env-filter", "json", "fmt"] }
• Added tracing-appender = "0.2"

src/utils/mod.rs

• Registered pub mod logging

Usage

# Default human-readable output (warnings and above)
starforge wallet list

# Debug level via RUST_LOG
RUST_LOG=debug starforge deploy --wasm contract.wasm

# JSON output for CI/CD log aggregators
starforge --log-format json wallet create alice

# Write rotating daily log files to a directory
starforge --log-dir ~/.starforge/logs wallet show alice

# JSON + file rotation combined
starforge --log-format json --log-dir /var/log/starforge tx history GABC...

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[Manuelshub]

@Nanle-code Please review

[Nanle-code]

@Manuelshub resolve conflict

[Manuelshub]

@Nanle-code Please review