chore(Algebra/QuadraticAlgebra): rename map/mapEquiv to changeGenerator

[xroblot]

Turns out map was a bad choice, being too general. changeGenerator says what the construction actually does. Renames it accordingly.

Prepared with Claude Code 🤖

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[github-actions]

PR summary 75b8e44e72

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

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Declarations diff (regex)

+ changeGenerator
+ changeGeneratorEquiv
+ changeGenerator_injective
+ changeGenerator_omega
+ changeGenerator_relation
+ discr_changeGenerator
- map_relation

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 75b8e44).

• +10 new declarations
• −5 removed declarations

+QuadraticAlgebra.changeGenerator
+QuadraticAlgebra.changeGenerator.congr_simp
+QuadraticAlgebra.changeGeneratorEquiv
+QuadraticAlgebra.changeGeneratorEquiv_apply
+QuadraticAlgebra.changeGeneratorEquiv_symm_apply
+QuadraticAlgebra.changeGenerator_injective
+QuadraticAlgebra.changeGenerator_omega
+QuadraticAlgebra.discr_changeGenerator
+QuadraticAlgebra.im_changeGenerator_apply
-QuadraticAlgebra.im_map_apply
-QuadraticAlgebra.map.congr_simp
-QuadraticAlgebra.mapEquiv_apply
-QuadraticAlgebra.mapEquiv_symm_apply
+QuadraticAlgebra.re_changeGenerator_apply
-QuadraticAlgebra.re_map_apply

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No changes to strong technical debt.

No changes to weak technical debt.

Current commit 75b8e44e72
Reference commit caa4dbde35

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).