[3.x] Create a unified redirect system

[emmadesilva]

Summary

• Introduce configured redirect handling in the framework and rebuild/build flows.
• Update sitemap, markdown, navigation, and console internals to align with the new redirect model.
• Refresh documentation, upgrade guides, and planning notes for Hyde v3.
• Adjust CI, release tooling, and package metadata to match the new behavior.

Testing

• Added and updated framework feature/unit coverage for redirects, sitemap generation, markdown, rebuild commands, and related views.
• Verified the affected workflow and package configuration changes at a high level.
• Not run (not requested)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (e7b362b) to head (05ee6aa).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##              master     #2517   +/-   ##
===========================================
  Coverage     100.00%   100.00%           
- Complexity      1676      1677    +1     
===========================================
  Files            170       170           
  Lines           4187      4185    -2     
===========================================
- Hits            4187      4185    -2     

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