Enhance fixed-point methods and optimization methods

[HugoMVale]

Summary

Comparison baseline: next vs main using git diff main...next (merge-base diff), Python sources only under polykin.

• 40 source Python files changed
• 12 new modules/files
• 1 module removed
• Main impact area: polykin.math (new optimization/fixpoint/root-solving structure and machine constants split)

New Modules

1. damped.py
2. dem.py
3. steffensen.py
4. machine.py
5. init.py
6. brent.py
7. globalmethods.py
8. qnewton.py
9. results.py
10. secant.py
11. simplex.py
12. qnewton.py

Important Fixes

1. init.py: top-level math API surface expanded (machine, optimization exports).
2. init.py: roots API export path changed (now re-exporting qnewton, no longer vector).
3. math.py: machine constants removed from this module (eps, huge, tiny) and moved to dedicated machine module.
4. ndiff.py: substantial numerical differentiation updates.
5. anderson.py: nontrivial algorithm-level changes.
6. wegstein.py: iterative solver internals adjusted.
7. scalar.py: scalar root solver internals updated.
8. special.py: special-function implementation path adjusted.
9. Removed module path: src/polykin/math/roots/vector.py (replaced by new organization around qnewton and optimization helpers).

Minor Fixes

1. binary.py
2. fitting.py
3. multicomponent.py
4. penultimate.py
5. terminal.py
6. gold.py
7. diffusion.py
8. desorption.py
9. entry.py
10. init.py
11. jcr.py
12. results.py
13. base.py
14. tait.py
15. base.py
16. cubic.py
17. vle.py
18. docs.py
19. typing.py

Compatibility Notes

• External imports from polykin.utils.math for machine constants should migrate to polykin.math.machine.
• Direct imports from removed path polykin.math.roots.vector should migrate to currently exported roots/optimization entry points.

[codecov]

Codecov Report

❌ Patch coverage is 88.89816% with 133 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.63%. Comparing base (e40eac2) to head (ded48c7).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main       #3      +/-   ##
==========================================
- Coverage   92.06%   91.63%   -0.44%     
==========================================
  Files          98      109      +11     
  Lines        5359     6154     +795     
==========================================
+ Hits         4934     5639     +705     
- Misses        425      515      +90