Add disk changes to end-to-end scripts

[Firehed]

Summary

Stacked on #684.

Adds disk changes to end-to-end scripts and moves the external-change tests onto them.

Steps

All in Step/:

• Close closes an open document.
• Copy and Delete change the disk as another program would, without telling the server. Copy puts a prepared variant in place, so no PHP is written inline; the variants live in DiskChange/ in the fixture project, outside the autoload paths. Scripts already run against a throwaway copy of the project (Add script-driven end-to-end tests with recorded transcripts #680), so fixtures are never mutated.
• ReportChanges sends one workspace/didChangeWatchedFiles listing typed file events (FileChange, FileChangeType).

Scripts

Each declares watched-file support and asks for definitions in src/DiskChange/Consumer.php, expecting NoAnswer() before a change and LandsOn after it (or the reverse for the deletion):

• a reported edit to an unopened class file;
• a checkout of two files, reported together;
• a deletion, reported as Deleted;
• a class created after a failed lookup, reported as Created;
• an edit to an open file's disk copy, which is ignored while the file is open and seen once it is closed;
• an edit to an autoload.files entry, reported and unreported.

What the scripts show about invalidation: class files are read again on every query, because what a file declares is cached under its path and text. An edit to a class file is therefore seen whether or not it is reported. The autoload.files index is rebuilt only on a report, so an unreported edit there is not seen. Both behaviors are stated as expectations; the unreported autoload.files case will change if a stand-in file watcher (#647) lands.

Originals

• ExternalFileChangeInvalidationTest is removed. Its enumeration case is covered only by name lookup here, and only for the added symbol, not the removed one, since enumeration surfaces through expression-position completion, which waits on PHP built-ins are read from the server's own PHP, not the project's #401.
• The watched-files case in ServerTest is removed, with the helpers only it used. It used Server::forProject and the container.
• DefinitionIntegrationTest is removed. disk-close-rereads shows that an open buffer wins over the disk, which its remaining case covered.

Coverage: ExternalFileChangeInvalidationTest covered nothing, and the ServerTest case covered nothing other tests do not. Removing DefinitionIntegrationTest leaves Server::forProject's fallback to the working directory uncovered in-process; every end-to-end script runs it, which coverage cannot see.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.67%. Comparing base (16b9e8f) to head (1f2a388).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@                     Coverage Diff                      @@
##             e2e-definition-handler     #685      +/-   ##
============================================================
- Coverage                     99.73%   99.67%   -0.07%     
  Complexity                     1900     1900              
============================================================
  Files                           135      135              
  Lines                          4873     4873              
============================================================
- Hits                           4860     4857       -3     
- Misses                           13       16       +3     

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