Extract DispatchEngine and slim Router to a route registry

[alganet]

Move the request execution algorithm out of Router into a dedicated DispatchEngine so the router can focus on route definition and registry concerns.

Changes:

• add DispatchEngine to own dispatch lifecycle logic: routeless handling, method override resolution, virtual-host path adjustment, route matching, routine matching, OPTIONS handling, and Allow/404/400/405 materialization
• make Router delegate dispatch(), dispatchContext(), and run() to the engine instead of performing request execution itself
• keep Router focused on route registration, route sorting, global routine attachment, and convenience entry points
• add small Router accessors needed by the engine for route registry and virtual-host lookup
• update low-level router tests and coverage annotations to reflect the new engine boundary

Verification:

• composer qa
• changed executable lines verified at 100% coverage

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.89%. Comparing base (2cf5a76) to head (94b10dd).

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #166      +/-   ##
============================================
- Coverage     97.14%   96.89%   -0.25%     
- Complexity      445      450       +5     
============================================
  Files            27       28       +1     
  Lines          1085     1096      +11     
============================================
+ Hits           1054     1062       +8     
- Misses           31       34       +3     

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