Perf: cache docblock FQCN lookups

[dereuromark]

Summary

Cache file-level work in FullyQualifiedClassNameInDocBlockSniff and avoid reprocessing the same doc block multiple times in a single phpcs pass.

This does two things:

• deduplicates doc block processing inside the sniff's current broad registration set (T_CLASS, T_INTERFACE, T_TRAIT, T_FUNCTION, T_VARIABLE, T_COMMENT), so the same doc block is only parsed once per pass;
• caches the file namespace and parsed use statements for the lifetime of that pass instead of rebuilding them for every class-name lookup.

The cache is pass-scoped, not content-scoped: it resets when token processing restarts from an earlier stack pointer, which is what phpcbf does after re-tokenizing a file for a new fix loop.

Why

After #63 and #64 landed, PhpCollective.Commenting.FullyQualifiedClassNameInDocBlock became the dominant repo-local hotspot on large docblock-heavy files.

The old code had two expensive patterns:

• parseUseStatements() walked the whole file every time findUseStatementForClassName() was called;
• the same related doc block could be processed repeatedly because multiple registered token types on the same declaration path all resolved to the same doc block.

That meant a large method-heavy file with repeated @param / @return / @throws tags paid for the same file-level scans many times.

Behavior

This also removes duplicate error reporting for the same doc block. The existing fixture still fixes to the same output, but the unique violation count drops from 11 to 7, which is what the updated test now asserts.

Benchmark

Measured on a synthetic large file with 430 repeated methods and docblocks:

• before: PhpCollective.Commenting.FullyQualifiedClassNameInDocBlock about 49.99s
• after: PhpCollective.Commenting.FullyQualifiedClassNameInDocBlock about 1.35s

Verification

• composer cs-fix
• composer test
• composer stan