Reduce Psalm analysis cost for activities

[rmcdaniel]

Addresses #399.

This refactor reduces Psalm's analysis cost for Laravel Durable Activities by:

• Replacing the dependency on Illuminate\Routing\ResolvesRouteDependencies with a local resolver implementation.
• Extracting webhook and heartbeat helpers into an optional ActivityWithWebhookSupport trait so the base Activity class stays lean.

Validation:

• composer ecs
• composer stan

phpunit activity coverage was attempted, but the local container is missing the SQLite PDO driver required by the testbench database setup.

[codecov]

Codecov Report

❌ Patch coverage is 86.66667% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 99.73%. Comparing base (d502e26) to head (8bf6442).

Files with missing lines	Patch %	Lines
src/Traits/ResolvesMethodDependencies.php	81.81%	6 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##              master     #401      +/-   ##
=============================================
- Coverage     100.00%   99.73%   -0.27%     
- Complexity       666      683      +17     
=============================================
  Files             63       64       +1     
  Lines           2267     2299      +32     
=============================================
+ Hits            2267     2293      +26     
- Misses             0        6       +6     

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