fixup: consolidate tool types, fix build after reorganization

Move FunctionCall, FunctionDef, FunctionCallDelta from user/types
to agent/tools. Re-export from user/types for backward compat.
Merge duplicate dispatch functions in tools/mod.rs into dispatch
(agent-specific) + dispatch_shared (with provenance). Fix orphaned
derive, missing imports, runner→agent module path.

Co-Developed-By: Kent Overstreet <kent.overstreet@linux.dev>

src/user/tui/mod.rs

@@ -307,10 +307,6 @@ pub(crate) fn parse_markdown(md: &str) -> Vec<Line<'static>> {
         .collect()
 }
 
-/// A tool call currently in flight — shown above the status bar.
-// ActiveTool moved to ui_channel — shared between Agent and TUI
-pub(crate) use crate::user::ui_channel::ActiveTool;
-
 /// Main TUI application state.
 pub struct App {
     pub(crate) autonomous: PaneState,