fix(metassr-watcher): replace eprintln! with tracing::error! for consistent logging

[abhicodes0324]

Problem

FileWatcher uses eprintln! to report watch errors, while the rest of the codebase uses tracing for all logging:

eprintln!("Watch Error: {err}");

metassr-server, metassr-api-handler, and metassr-bundler all use tracing::{debug, info, warn, error} consistently. metassr-watcher is the only crate that bypasses this with a raw eprintln!, meaning file watcher errors won't appear in log files and won't respect log level filtering.

Changes

crates/metassr-watcher/src/lib.rs

• eprintln!("Watch Error: {err}") → error!("Watch error: {err}")
• Added use tracing::error

crates/metassr-watcher/Cargo.toml

• Added tracing.workspace = true dependency

Note

Could not verify output locally due to the MetaCall native dependency requirement. The change is a mechanical replacement verified against the existing tracing usage pattern throughout the codebase.