Tag absolute value lemmas with @[push]

[ldct]

Summary

• Tag abs_mul, abs_pow, abs_mul_self, abs_inv, abs_div, abs_zpow, and abs_neg with @[push] so that push abs can distribute absolute value through arithmetic expressions.
• Add tests in MathlibTest/push.lean including a compound example: |a ^ n * b⁻¹ / (-a)| = |a| ^ n * |b|⁻¹ / |a|

Test plan

• lake env lean MathlibTest/push.lean passes
• CI

🤖 Generated with Claude Code

[github-actions]

PR summary 98261a9c88

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

No declarations were harmed in the making of this PR! 🐙

You can run this locally as follows

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

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

The doc-module for scripts/pr_summary/declarations_diff.sh contains some details about this script.

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No changes to technical debt.

You can run this locally as

./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).

[mathlib-merge-conflicts]

This pull request has conflicts, please merge master and resolve them.