chore(dev): replace the MinIO image by pgsty/silo in the development (#18238)

[A. Jard (aHenryJard)]

Proposed changes

• Backport of chore(dev): replace the MinIO image by pgsty/silo in the development and CI stacks (#18238) #18239

• Switch both compose files to pgsty/silo: pinned to RELEASE.2026-09-03T13-18-01Z in dev so that Renovate keeps following it, latest in CI as today. Service names, ports, credentials, command and healthcheck stay as they are.

• Update the documentation and the contributor guides that name MinIO as the object storage of the stack (deployment docs, dev README, Copilot instructions).

No change to the platform itself: the minio:* configuration keys and the S3 client are untouched, and any S3-compatible service remains supported.

Related issues

• closes chore(dev): replace the MinIO image by pgsty/silo in the development and CI stacks #18238

How to test this PR

Checklist

• I consider the submitted work as finished
• I tested the code for its functionality
• I wrote test cases for the relevant use cases (coverage and e2e)
• I added/updated the relevant documentation (either on GitHub or on Notion)
• Where necessary, I refactored code to improve the overall quality

Further comments

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 22.31%. Comparing base (e3ecf51) to head (bdbfd1d).

Additional details and impacted files

@@                Coverage Diff                 @@
##           lts/7.260811.0   #18309      +/-   ##
==================================================
- Coverage           26.09%   22.31%   -3.79%     
==================================================
  Files                3386     3386              
  Lines              138061   138061              
  Branches            37385    37385              
==================================================
- Hits                36028    30806    -5222     
- Misses             102033   107255    +5222     

Flag	Coverage Δ
opencti-client-python	48.37% <ø> (ø)
opencti-front	11.06% <ø> (ø)
opencti-graphql	34.79% <ø> (-11.05%)	⬇️

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