feat: add agentic callbacks template

[mrh997]

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[codecov]

Codecov Report

❌ Patch coverage is 63.55932% with 43 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.86%. Comparing base (73d27eb) to head (5c345ce).
⚠️ Report is 1 commits behind head on release/agentic_model.

Files with missing lines	Patch %	Lines
utils/callbacks/template.go	65.21%	30 Missing and 2 partials ⚠️
components/model/callback_extra.go	0.00%	6 Missing ⚠️
compose/chain.go	0.00%	1 Missing ⚠️
compose/chain_branch.go	0.00%	1 Missing ⚠️
compose/chain_parallel.go	0.00%	1 Missing ⚠️
compose/component_to_graph_node.go	0.00%	1 Missing ⚠️
compose/graph.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@                    Coverage Diff                    @@
##           release/agentic_model     #681      +/-   ##
=========================================================
+ Coverage                  78.79%   78.86%   +0.06%     
=========================================================
  Files                        132      130       -2     
  Lines                      13263    13278      +15     
=========================================================
+ Hits                       10451    10472      +21     
+ Misses                      1939     1937       -2     
+ Partials                     873      869       -4     

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