feat: add REPL mode for interactive contract exploration

[ScriptedBro]

Adds a repl mode for interactive contract exploration so users can call functions, inspect storage, and keep contract state alive across commands in a single session.

What changed

• Wired REPL function calls to the real ContractExecutor (removed simulated call output)
• Kept a persistent executor instance across REPL commands so state is preserved
• Implemented host-backed storage snapshots for storage inspection output
• Enabled REPL auth mocking for contracts that use require_auth() (e.g. token examples)
• Added type-aware REPL argument handling using contract spec signatures
• Added REPL address aliasing so inputs like Alice / Bob can be used for Address params
• Preserved rustyline history behavior (history command + up-arrow navigation + persisted history)
• Fixed false-positive storage alerts when no alert filters are configured

Acceptance Criteria

• repl subcommand launches interactive session
• Function calls work and show results
• Storage inspectable at any time with storage
• Command history navigable with up-arrow
• Clean exit with exit or Ctrl+D

Validation

• Built release binary: cargo build --release --bin soroban-debug
• Verified interactive REPL launch and prompt
• Verified token contract calls in REPL (initialize, mint) with persisted state
• Ran tests:
  • cargo test repl:: --lib
  • cargo test inspector::storage:: --lib

Closes #209

Issue: #209