chore: replace enechange references with iwamot

[iwamot]

Summary

Migrate repository references from enechange to iwamot. The project was originally developed under the iwamot account, then transferred to enechange. Development continues on the iwamot fork.

• Replace ghcr.io/enechange/collmbo with ghcr.io/iwamot/collmbo in feature docs
• Update SECURITY.md advisory URL to iwamot/collmbo
• Add Takashi Iwamoto copyright to LICENSE
• Update auto-approve.yml bot name to iwamot-renovate[bot]
• Update CI and Codecov badge URLs in README.md

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 50.96%. Comparing base (fd65a4d) to head (c7f905a).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1066   +/-   ##
=======================================
  Coverage   50.96%   50.96%           
=======================================
  Files          26       26           
  Lines        1244     1244           
  Branches      178      178           
=======================================
  Hits          634      634           
  Misses        606      606           
  Partials        4        4           

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