Prep for patch release

[jinningwang]

• Add demo_AGC to demonstrate detailed SFR study
• Add ExpressionCalc to handle post-solving calculation
• Rename type='eq' to is_eq=False in Constraint to avoid overriding built-in attribute
• Several formatting improvements

[codecov]

Codecov Report

Attention: Patch coverage is 88.11189% with 17 lines in your changes are missing coverage. Please review.

Project coverage is 78.10%. Comparing base (61f7907) to head (7e2a68f).

Files	Patch %	Lines
ams/opt/omodel.py	80.48%	8 Missing ⚠️
ams/cli.py	0.00%	3 Missing ⚠️
ams/routines/dcopf.py	77.77%	2 Missing ⚠️
ams/system.py	0.00%	2 Missing ⚠️
ams/routines/dcpf.py	0.00%	1 Missing ⚠️
ams/routines/routine.py	88.88%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #58      +/-   ##
==========================================
+ Coverage   76.08%   78.10%   +2.02%     
==========================================
  Files          58       58              
  Lines        4754     4741      -13     
==========================================
+ Hits         3617     3703      +86     
+ Misses       1137     1038      -99     

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[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
❌ -2.30% (target: -1.00%)	✅ 89.17%

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (61f7907)	10810	5802	53.67%
Head commit (7e2a68f)	11444 (+634)	5879 (+77)	51.37% (-2.30%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#58)	157	140	89.17%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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_{You may notice some variations in coverage metrics with the latest Coverage engine update. For more details, visit the documentation}

[jinningwang]

Good to go.