CAMEL-23226: Migrate Shell to JLine 4 Shell API

[gnodet]

JIRA: CAMEL-23226

Summary

Migrate the Camel JBang shell command from the old picocli-shell-jline3 bridge pattern to the new JLine 4 Shell builder API.

• Replace ~90 lines of manual REPL boilerplate with JLine 4's Shell.builder() fluent API
• Switch from picocli-shell-jline3 to jline-picocli (JLine 4's native picocli integration)
• Add built-in PosixCommandGroup and InteractiveCommandGroup for POSIX utilities (ls, cat, grep, etc.) and interactive commands
• Enable history, help, script, and variable commands via the Shell builder
• Retain camel> prompt, history file at ~/.camel-jbang-history, tab completion with 50 max candidates

Test plan

• Verify camel shell launches interactive shell with camel> prompt
• Tab completion works for camel commands
• History persistence works across sessions
• Ctrl-C / Ctrl-D exits cleanly

[github-actions]

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[github-actions]

🧪 CI tested the following changed modules:

• dsl/camel-jbang/camel-jbang-core

All tested modules (26 modules)

• Camel :: Coverage
• Camel :: Coverage [pom]
• Camel :: JBang :: Core
• Camel :: JBang :: Core [jar]
• Camel :: JBang :: Integration tests
• Camel :: JBang :: Integration tests [jar]
• Camel :: JBang :: MCP
• Camel :: JBang :: MCP [jar]
• Camel :: JBang :: Main
• Camel :: JBang :: Main [jar]
• Camel :: JBang :: Plugin :: Edit
• Camel :: JBang :: Plugin :: Edit [jar]
• Camel :: JBang :: Plugin :: Generate
• Camel :: JBang :: Plugin :: Generate [jar]
• Camel :: JBang :: Plugin :: Kubernetes
• Camel :: JBang :: Plugin :: Kubernetes [jar]
• Camel :: JBang :: Plugin :: Route Parser
• Camel :: JBang :: Plugin :: Route Parser [jar]
• Camel :: JBang :: Plugin :: Testing
• Camel :: JBang :: Plugin :: Testing [jar]
• Camel :: JBang :: Plugin :: Validate
• Camel :: JBang :: Plugin :: Validate [jar]
• Camel :: Launcher
• Camel :: Launcher [jar]
• Camel :: Launcher :: Container
• Camel :: Launcher :: Container [pom]

[gnodet]

Claude Code on behalf of Guillaume Nodet

Closing — superseded by #22170 which includes all changes from this PR plus additional enhancements.