client: automatic layout save and restore

[coletrammer]

Summary

Closes #21

Check List

• Self-review the code
• Update tests if necessary
• Update docs if necessary

[codecov]

Codecov Report

Attention: Patch coverage is 65.03856% with 136 lines in your changes missing coverage. Please review.

Project coverage is 65.92%. Comparing base (784f3bc) to head (82483f2).
Report is 11 commits behind head on main.

Files with missing lines	Patch %	Lines
src/save_layout.cpp	0.00%	59 Missing ⚠️
src/actions.cpp	0.00%	30 Missing ⚠️
src/layout_state.cpp	83.92%	9 Missing ⚠️
src/tab.cpp	80.85%	9 Missing ⚠️
src/ttx.cpp	80.55%	7 Missing ⚠️
src/input.cpp	0.00%	6 Missing ⚠️
lib/src/layout.cpp	93.15%	5 Missing ⚠️
src/save_layout.h	0.00%	5 Missing ⚠️
src/session.cpp	91.66%	3 Missing ⚠️
lib/src/pane.cpp	80.00%	1 Missing ⚠️
... and 2 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #22      +/-   ##
==========================================
- Coverage   66.28%   65.92%   -0.36%     
==========================================
  Files          62       66       +4     
  Lines        4933     5289     +356     
  Branches      698      750      +52     
==========================================
+ Hits         3270     3487     +217     
- Misses       1663     1802     +139     

Flag	Coverage Δ
Linux	65.92% <65.03%> (-0.36%)	⬇️

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