Support builder

[eckfel]

Summary

Adds the builder command group for creating new workflows interactively through a conversational agent, along with supporting infrastructure and documentation updates.

Builder (builder start/send/poll/respond/...)

• New builder command with 10 subcommands: start, send, poll, respond, status, workflow, messages, save, interrupt, end
• SSE-based streaming client (builder-stream.ts) for real-time agent communication
• Local session persistence (session.ts) so auth and session state carry across commands
• Support for single-value and multi-input agent responses
• Non-blocking send with poll-based status checking (processing, done, error, waiting_for_input, idle)
• Opens live builder URL in default browser on start

CLI improvements

• Usage examples added to --help for all 39 subcommands
• encrypted_keys added to auto-stripped read-only fields in workflows update
• Base64 content stripped from builder messages output for readability
• ApiClient.patch() method added
• output.ts helpers for consistent JSON/stderr output

Auth & vault

• auth login now accepts --encryption-key for vault operations
• Minor vault command improvements

Skills & documentation

• Skill files restructured: cloudcruise.md + references/workflow-dsl.md
• Skill content expanded with builder usage patterns, send/poll workflow, and input handling
• Workflow DSL reference updated
• README updated with vault, builder, and expanded command reference table
• install --skills updated to handle new file structure