Handlers now accept their actual dependencies directly:
- Root handlers: ModelCache, Broker, context.Context, etc.
- Session handlers: *SessionNode, removeFn, renameFn
- Agent handlers: *agent.Agent, *AgentLog, *SessionNode
Ctl dispatch tables are now per-instance closures built at binding
time rather than package-level vars with generic Hctx.
Also inlined the intermediate internalBinding type — adapt functions
now build fsedsl.Binding directly from raw data.
Removed: Hctx struct, rdwrHandler type, rdwrDispatch func,
bypassBindings helper, processBindings helper, internalBinding type.
1474eeaaed