Fix UndefVarError in get_exct(::ConcreteCallInfo)

[jishnub]

get_exct(::ConcreteCallInfo) binds its argument as cici but references ceci in the body, so any call throws UndefVarError: ceci. The sibling accessors (get_ci, get_rt, get_effects) all use ceci.

julia> cci = Cthulhu.ConcreteCallInfo(Cthulhu.PureCallInfo(Any[], Float64), Any[]);

julia> Cthulhu.get_exct(cci)
ERROR: UndefVarError: `ceci` not defined in `Cthulhu`

After this change it returns Union{}.

The terminal UI never hits this, since show_callinfo(::ConcreteCallInfo) calls __show_limited without an exct argument — but it is reachable for anything that queries the accessors directly.

🤖 Generated with Claude Code

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 0.00%. Comparing base (2c33b9a) to head (fce3219).
⚠️ Report is 99 commits behind head on master.

Files with missing lines	Patch %	Lines
src/compiler/callsite.jl	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #706    +/-   ##
=======================================
  Coverage    0.00%   0.00%            
=======================================
  Files           9      22    +13     
  Lines        1556    1808   +252     
=======================================
- Misses       1556    1808   +252     

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[serenity4]

Merging this as it is a very simple typo fix. Thanks!