chore: Add JSON-RPC server

[rsenden]

feat: `fcli util rpc-server start`: New JSON-RPC server command for programmatic fcli access (hidden, for internal use only for now)

feat: `fcli util mcp-server start`: Add `--import` option for importing action YAML files, exposing exported action functions as MCP tools or resource templates

feat: `fcli util mcp-server start`: `--module` option is now optional (at least one of `--module` or `--import` must be specified)

feat: `fcli util mcp-server start`: Support MCP resource templates via function `meta.mcp.resource` metadata

feat: `fcli util all-commands list`: Enrich output with module category (`PRODUCT`/`CONFIG`/`UTIL`) and session requirement metadata

feat: fcli action framework: Add `functions` support — define reusable functions in action YAML with typed arguments, return values, and streaming (lazy `fn.yield`) capabilities; invoke via `#fn.call('name', args...)` SpEL function

feat: fcli action framework: Add `with.product` step for establishing product context (SSC/FoD) within action steps, making product-specific SpEL functions and REST targets available without running product-specific action commands

feat: fcli action framework: Add `fn.yield` step for emitting records from streaming functions, with automatic consumer termination detection

feat: fcli action framework: Add `sleep` step for pausing execution for a SpEL-evaluated duration in milliseconds

feat: fcli action framework: Add `#fcli.listCommands()`, `#fcli.listCommands(query)`, `#fcli.getCommandSpec(command)`, and `#fcli.getCommandArgs(command)` SpEL functions for querying available fcli commands from within action YAML

fix: `fcli util mcp-server start`: Fix option `required` reporting for options inside optional argument groups

fix: Fix some potential issues related to fcli stdio handling

fix: Fix potential concurrent modification of global values in multi-threaded contexts (e.g., async jobs in RPC/MCP servers)