Remember what a document declares, per file

[Firehed]

Second of five stacked PRs, on top of the document source. #646 is the total view.

What was wrong

• Reading a file, parsing it, scanning it, and building its infos was written out in three backends.
• The symbol cache remembered answers by name, while what changes is a file. It kept side tables to bridge the two and dropped unrelated entries on every change.

What this does

• DeclarationSourceInterface is the one way to get what a document declares. The three backends hold it in place of a parser, a scanner, and an info factory.
• CachingDeclarationSource remembers declarations by the file's path and text together. Changed text is a different key, so nothing is invalidated. It holds 2,000 documents and drops the least recently used.
• CachingSymbolSource is deleted.
• TextDocument indexes line starts on first use. A document read only for what it declares is never asked for a position, and the index was most of the cost of a cached lookup.

Behaviour changes

• A class deleted or renamed in an unsaved buffer no longer resolves from disk.
• Identical text re-sent in a later message is not parsed again.

Measured

openemr, class-name completion while typing, median of seven sessions, change message plus request.

Typed	main	This branch
new Pa	165 ms	165 ms
new Pat	107 ms	103 ms
new Pati	123 ms	117 ms
new Pat again	116 ms	89 ms

Tests removed or rewritten

Each at Eric's direction.

• CachingSymbolSourceTest is deleted with its subject.
• CompositeInvalidatableTest drove the composite through the deleted class. It now changes the disk under each of the three members and asks that member.
• ServerTest::testParsesAreScopedToOneMessage asserted that identical text re-sent must parse again. It is now testTheSyncPathParsesATextOnce.

DeclarationSymbolInfoFactory::fromDeclarations() has no caller left in src/. Two test files still use it.

Enforcement edits

Edit	Class
phpstan.neon lookupConstant() allowlist: drop CachingSymbolSource	Tighten

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.65%. Comparing base (2fc97b4) to head (afa7542).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #649      +/-   ##
============================================
- Coverage     99.65%   99.65%   -0.01%     
+ Complexity     1916     1903      -13     
============================================
  Files           135      136       +1     
  Lines          4946     4882      -64     
============================================
- Hits           4929     4865      -64     
  Misses           17       17              

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