client+terminal: Recognize and use OSC 7

[coletrammer]

Summary

Closes #18. This is really cool, because now the layout save/restore feature also remembers the pane's current working directory. And splitting new panes or creating new tabs will use the current active pane's current working directory. This is a massive usability improvement.

Because we are using OSC 7, this relies on shell integration. In my configuration, I'm relying on the outer terminal's shell integration.

Check List

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

[codecov]

Codecov Report

Attention: Patch coverage is 68.18182% with 35 lines in your changes missing coverage. Please review.

Project coverage is 66.13%. Comparing base (82483f2) to head (7d27c03).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/src/pane.cpp	29.72%	26 Missing ⚠️
src/actions.cpp	0.00%	6 Missing ⚠️
lib/src/layout.cpp	90.00%	1 Missing ⚠️
lib/src/terminal.cpp	92.30%	1 Missing ⚠️
src/tab.cpp	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #23      +/-   ##
==========================================
+ Coverage   65.92%   66.13%   +0.20%     
==========================================
  Files          66       68       +2     
  Lines        5289     5368      +79     
  Branches      750      763      +13     
==========================================
+ Hits         3487     3550      +63     
- Misses       1802     1818      +16     

Flag	Coverage Δ
Linux	66.13% <68.18%> (+0.20%)	⬆️

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