feat: add direct .trb file execution without intermediate files

[yhk1038]

Summary

Closes #26

• Add t-ruby command as the main executable for running .trb files directly
• Add trc run subcommand that delegates to t-ruby via exec
• No intermediate .rb or .rbs files are generated - code runs in memory
• Similar to Node.js's --experimental-strip-types functionality

Usage

# Run a .trb file directly
t-ruby hello.trb

# Run with arguments passed to ARGV
t-ruby script.trb arg1 arg2

# Or use trc run (internally calls t-ruby)
trc run hello.trb

Test plan

• t-ruby --help shows help message
• t-ruby --version shows version
• t-ruby hello.trb executes T-Ruby code
• t-ruby script.trb foo bar passes arguments to ARGV
• trc run hello.trb delegates to t-ruby
• Error handling for missing files
• No intermediate .rb files generated