fix: handle literal colons in URL paths for denco router

[KuaaMU]

Summary

Handle literal colons in URL path segments for the denco router.

Motivation

Fixes #352. The denco router uses : as a parameter delimiter, but : is a valid character in URL path segments per RFC 3986. Routes like /allow/{serverName}/tokenlist:add were being misinterpreted — the : in tokenlist:add was treated as a parameter prefix.

Changes

• Added escapeLiteralColons() function that replaces literal : with %3A in path segments that aren't parameter delimiters
• Applied in AddRoute(), Lookup(), and OtherMethods() — the three places where paths interact with the denco router
• Added tests: unit test for the escape function, integration tests with denco router for static paths, parametric paths, and mixed cases

Verification

go test ./middleware/... -v -run "Colon|Literal"
go test work ./...

All tests pass across all 14 packages.

[fredbi]

Thanks for this addition. Looks good to me.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.69%. Comparing base (ab827de) to head (5a98e19).
⚠️ Report is 4 commits behind head on master.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #422      +/-   ##
==========================================
+ Coverage   81.68%   81.69%   +0.01%     
==========================================
  Files          50       50              
  Lines        3379     3381       +2     
==========================================
+ Hits         2760     2762       +2     
  Misses        507      507              
  Partials      112      112              

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