feat(Order/Fin): conditions for Fin.insertNth to be monotone or strictly monotone

[joelriou]

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[github-actions]

PR summary a39b5f0532

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference
Mathlib.Order.Fin.InsertNth (new file)	367

---

Declarations diff (regex)

+ insertNth_last_monotone
+ insertNth_monotone
+ insertNth_zero_monotone
+ strictMono_insertNth
+ strictMono_insertNth_last
+ strictMono_insertNth_zero

You can run this locally as follows

## from your `mathlib4` directory:
git clone https://github.com/leanprover-community/mathlib-ci.git ../mathlib-ci

## summary with just the declaration names:
../mathlib-ci/scripts/pr_summary/declarations_diff.sh <optional_commit>

## more verbose report:
../mathlib-ci/scripts/pr_summary/declarations_diff.sh long <optional_commit>

The doc-module for scripts/pr_summary/declarations_diff.sh in the mathlib-ci repository contains some details about this script.

Declarations diff (Lean)

✅ Lean-aware diff — post-build, computed from the Lean environment (commit a39b5f0).

• +6 new declarations
• −0 removed declarations

+Fin.insertNth_last_monotone
+Fin.insertNth_monotone
+Fin.insertNth_zero_monotone
+Fin.strictMono_insertNth
+Fin.strictMono_insertNth_last
+Fin.strictMono_insertNth_zero

---

No changes to strong technical debt.

No changes to weak technical debt.

Current commit a39b5f0532
Reference commit c368140668

This script lives in the mathlib-ci repository. To run it locally, from your mathlib4 directory:

git clone https://github.com/leanprover-community/mathlib-ci.git ../mathlib-ci
../mathlib-ci/scripts/reporting/technical-debt-metrics.sh pr_summary

• The relative value is the weighted sum of the differences with weight given by the inverse of the current value of the statistic.
• The absolute value is the relative value divided by the total sum of the inverses of the current values (i.e. the weighted average of the differences).