feat: add NATS service discovery tools

[bougyman]

Summary

• add NATS Service API discovery helpers and command-line tools
• expose service information, statistics, and endpoint subject maps
• declare the minimal trailblazer-operation runtime dependency

Closes #58

Validation

• bundle exec rake ci (49 runs, 104 assertions; 0 failures, 0 errors, 0 skips)

[Copilot]

🟡 Changes recommended

Unresolved critical and moderate findings remain in response handling and CLI behavior and coverage.

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Pull request overview

Adds NATS Service API discovery helpers, Trailblazer operations, and four CLI tools for service information, statistics, and endpoint subject maps.

Changes:

• Implements INFO, PING, STATS, and subject-map discovery.
• Adds CLI filtering, formatting, connection handling, and executables.
• Adds integration coverage and dependency updates.

File summaries

File	Reviewed change / note
test/integration/nats_service_discovery_test.rb	Integration coverage for discovery workflows.
lib/leopard/nats_service_discovery/operation/verb.rb	Shared verb operation behavior.
lib/leopard/nats_service_discovery/operation/subject_map.rb	Builds endpoint subject maps.
lib/leopard/nats_service_discovery/operation/stats.rb	Implements service statistics discovery.
lib/leopard/nats_service_discovery/operation/services.rb	Summarizes discovered services.
lib/leopard/nats_service_discovery/operation/ping.rb	Implements PING discovery.
lib/leopard/nats_service_discovery/operation/info.rb	Implements INFO discovery.
lib/leopard/nats_service_discovery/operation/discovery_options.rb	Shared discovery operation options.
lib/leopard/nats_service_discovery/operation/connect.rb	Implements connection handling.
lib/leopard/nats_service_discovery/operation/collect.rb	Collects responses from arbitrary subjects.
lib/leopard/nats_service_discovery/operation.rb	Loads discovery operations.
lib/leopard/nats_service_discovery/cli.rb	Shared CLI parsing and output helpers. Line 44: moderate finding (1 vote) regarding reconnect behavior. Line 24: moderate finding (2 votes) requesting CLI-level or subprocess coverage.
lib/leopard/nats_service_discovery.rb	Core response collection and subject mapping. Line 106: critical finding (2 votes) regarding rescuing connection failures from subscription setup.
leopard.gemspec	Declares the Trailblazer runtime dependency.
Gemfile.lock	Locks dependency updates.
exe/leopard-services	Adds the service summary command.
exe/leopard-service-stats	Adds the service statistics command.
exe/leopard-service-map	Adds the endpoint subject-map command.
exe/leopard-service-info	Adds the service INFO command.

Review details

Suppressed comments (1)

lib/leopard/nats_service_discovery/cli.rb:44

• The CLI only passes server and creds, so NATS.connect keeps its default reconnect behavior. When the configured broker is unavailable, a one-shot command can retry for the client's reconnect window instead of returning to abort_with, making these discovery tools appear hung; disable reconnect (and optionally set a short connect timeout) for this CLI connection.

          result = Operation::Connect.call(server: opts[:server], creds: opts[:creds])

• Files reviewed: 18/19 changed files
• Comments generated: 2
• Review effort level: Lite

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