tui: compact tool selector with bidirectional cycle navigation

[flowq-C]

Description

This PR fixes three issues affecting custom agents (defined via config.session.custom_agents) in the New Session dialog.

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Fix 1: Tool selector overflow (render.rs)

The dialog renders all tools in a single horizontal line. With 5+ built-ins plus custom agents, the line overflows — custom agents become invisible and unreachable.

Before:

Tool: ● claude  ○ opencode  ○ codex  ○ gemini  ○ copilot  ○ cl-|
                                                            (truncated, unreachable)

After:

Tool: ← ● claude-gemma  [6/10]  →

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Fix 2: Bidirectional navigation broken (mod.rs)

Both ← and → performed the same action (forward increment). ← was effectively broken.

Split into two separate handlers: → increments, ← decrements with wrap-around.

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Fix 3: YOLO mode ignored for custom agents (instance.rs)

Custom agents are not in the built-in AGENTS list, so get_agent(&self.tool) returns None for them. This caused the YOLO flag to be silently skipped regardless of the YOLO toggle in the dialog — apply_yolo_mode was never called.

Fix: fall back to self.detect_as (already stored on the instance from agent_detect_as config) when the primary lookup returns None:

// Before:
let agent = crate::agents::get_agent(&self.tool);

// After:
let agent = crate::agents::get_agent(&self.tool)
    .or_else(|| crate::agents::get_agent(&self.detect_as));

This lets custom agents inherit the correct YoloMode from their declared agent_detect_as agent (e.g. --dangerously-skip-permissions for claude).

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Changes

• src/tui/dialogs/new_session/render.rs — compact selector display with counter
• src/tui/dialogs/new_session/mod.rs — split Left/Right handler, fix ← direction
• src/session/instance.rs — YOLO mode fallback via detect_as for custom agents

PR Type

• New Feature
• Bug Fix
• Refactor
• Documentation
• Infrastructure / CI

Checklist

• I understand the code I am submitting
• New and existing tests pass
• Documentation was updated where necessary
• For UI changes: included screenshot or recording

AI Usage

• No AI was used
• AI was used for drafting/refactoring
• This is fully AI-generated

AI Model/Tool used: Claude Sonnet 4.6 via Claude Code CLI

Any Additional AI Details you'd like to share: All three bugs were discovered while using custom Ollama cloud model aliases with AOE. Fixes were implemented, built locally, and tested before submitting.

• I am an AI Agent filling out this form (check box if true)

[Seluj78]

Thanks for the PR ! Can you edit the body to follow the template ?

Otherwise the fix you are proposing sounds good, I am on my phone so I can't test it further right now