feat(logging): tracing diagnostics with --log-format/--log-level (#51)

[hyperpolymath]

Add tracing + tracing-subscriber. Global --log-format=pretty|json and --log-level flags (precedence --log-level > RUST_LOG > info). The subscriber writes to stderr so the stdout data contract is never contaminated: JSON reports, the version string, the octad table, and the status/gc/validate report bodies stay on stdout verbatim. Only genuine diagnostics (schema parsing, file-write progress, "checking drift", "created manifest") become tracing events. JSON log schema documented in docs/logging.adoc + docs/logging.schema.json. New acceptance suite tests/logging_test.rs (6 tests): stdout purity, JSON-line schema validity, level filtering, RUST_LOG precedence.

Closes #51.

Summary

Changes

RSR Quality Checklist

Required

• Tests pass (just test or equivalent)
• Code is formatted (just fmt or equivalent)
• Linter is clean (no new warnings or errors)
• No banned language patterns (no TypeScript, no npm/bun, no Go/Python)
• No unsafe blocks without // SAFETY: comments
• No banned functions (believe_me, unsafeCoerce, Obj.magic, Admitted, sorry)
• SPDX license headers present on all new/modified source files
• No secrets, credentials, or .env files included

As Applicable

• .machine_readable/STATE.a2ml updated (if project state changed)
• .machine_readable/ECOSYSTEM.a2ml updated (if integrations changed)
• .machine_readable/META.a2ml updated (if architectural decisions changed)
• Documentation updated for user-facing changes
• TOPOLOGY.md updated (if architecture changed)
• CHANGELOG or release notes updated
• New dependencies reviewed for license compatibility (PMPL-1.0-or-later / MPL-2.0)
• ABI/FFI changes validated (src/interface/abi/ and src/interface/ffi/ consistent)

Testing

Screenshots