[FEAT] Adding Frieland Chapter 14

[henrydingliu]

Summary of Changes

Adding Friedland Chapter 14
Correcting some typos in the data file

Related GitHub Issue(s)

#588

AI/LLM Usage

most of the code was copy and paste from prior chapters
i used ai to turn screenshots of the friedland text into hardcoded arrays for asserting

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---

Note

Low Risk
Documentation and bundled sample-data corrections only; no library API or runtime behavior changes beyond users of the corrected CSV.

Overview
Adds Friedland Chapter 14 documentation (salvage/subrogation recoveries and reinsurance) as a new notebook wired into docs/_toc.yml. The notebook walks through Exhibit I (development, chain-ladder, ratio-based ultimate S&S, recoverables) and Exhibit II (QS/XOL samples plus stop-loss treaty tables), with assert checks against textbook figures.

Corrects friedland_auto_salsub.csv: reported/received salvage and related amounts are fixed so accident-year triangles follow the intended calendar-year progression (e.g. latest-age cells no longer carry values that belonged to other years/rows).

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[github-actions]

Pyright Type Completeness

View the full pyright --verifytypes output for this commit

Project (full chainladder package, at this PR's head): 15.0% of exported symbols fully typed (208 / 1383)

	Known	Ambiguous	Unknown	Total
Project (head)	208	111	1064	1383

Other symbols referenced but not exported by chainladder: 13

	Known	Ambiguous	Unknown	Total
Other (head)	3	1	9	13

Symbols without documentation:

• Functions without docstring: 328
• Functions without default param: 0
• Classes without docstring: 10

Patch (exported symbols added or changed by this PR): no exported symbol type-completeness changes detected.

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Stale Bugbot comment from a previous run.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.76%. Comparing base (a9c1326) to head (9b9fdee).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

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  Coverage   91.76%   91.76%           
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  Files          96       96           
  Lines        5477     5477           
  Branches      706      706           
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  Hits         5026     5026           
  Misses        327      327           
  Partials      124      124           

Flag	Coverage Δ
unittests	91.76% <ø> (ø)

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