feat: Turán numbers and their strict monotonicity

[Parcly-Taxel]

strictMonoOn_turanNumber and sum_mul_le_twice_turanNumber were initially proved by @Aristotle-Harmonic, then hand-polished.

Co-authored-by: Aristotle (Harmonic) aristotle-harmonic@harmonic.fun

[github-actions]

PR summary dfae8cda72

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

---

Declarations diff

+ mul_turanNumber_le
+ strictMonoOn_turanNumber
+ sum_mul_le_twice_turanNumber
+ turanGraph_one
+ turanNumber
+ turanNumber_add
+ turanNumber_eq

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.

---

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).