re #209 test: upgrade PHPUnit 11 → 12 and paratest 7.8 → 7.20

[tonydspaniard]

Part of #209 (does not close it). Upgrades the test toolchain one major version while keeping the framework's PHP 8.3 floor.

Why PHPUnit 12, not 13

Both PHPUnit 13 and paratest 7.22+ require PHP ≥ 8.4.1, so the literal "11 → 13" from #209 would force dropping PHP 8.3 (a breaking change / positioning decision). PHPUnit 12 (PHP ≥ 8.3) + paratest 7.20 (php 8.3||8.4||8.5, phpunit ^12.5||^13) is the ceiling that preserves 8.3 and still advances paratest 12 minors (7.8.5 → 7.20.0). The full 13 jump is deferred to a separate decision on the 8.3 floor.

Resolves to: phpunit/phpunit 12.5.29, phpunit/php-code-coverage 12.5.7, brianium/paratest 7.20.0.

Constraint bumps (^11.4 → ^12.5, paratest ^7 → ^7.20)

• composer.json (require-dev)
• src/Altair/TestReporter/composer.json (the published reporter package)
• both bin/altair-generated skeleton composer.json files

PHPUnit 12 breakages fixed

1. Config aborts the run with no coverage driver. PHPUnit 12 prints "No tests executed" when a <coverage> report is configured but pcov/xdebug is absent. Removed the redundant <coverage><clover> block from phpunit.xml.dist — CI passes --coverage-clover coverage.xml on the CLI, so the block was duplicative and only broke driverless local runs. <source> is kept (coverage scope + restrictNotices/restrictWarnings).
2. 13 deprecations — "Using with() on a test stub has no effect and is deprecated."* Removed the no-op with() argument-matchers from createStub() doubles in 4 Cookie/FormatNegotiator tests (they assert on output, not interaction). Dropped two now-unused imports.
3. 12 notices — "No expectations were configured for the mock object … use a test stub instead." Converted expectation-less createMock() / getMockBuilder() doubles to createStub() in CycleEntityManagerTest, CycleReadModelRepositoryTest, DispatcherMiddlewareTest, SessionBlockTest (the two mocks that do call expects() are left as mocks).

Verification

• Full suite green on PHPUnit 12.5.29: 6557 tests, 0 failures / 0 warnings / 0 deprecations / 0 notices. The only errors/skips are environment-gated (ext-mongodb/ext-redis absent locally; they pass on CI).
• The published test-reporter AltairExtension loads on PHPUnit 12 and emits a valid JSON report (result: pass, correct totals) — the Extension + event-subscriber API is unchanged.
• paratest 7.20.0 runs the suite in parallel.
• composer cs + composer stan (level 8, no baseline) + composer rector (whole-tree dry-run) all clean.

Docs

PHPUnit 11 → 12 across README.md, AGENT.md, CLAUDE.md, docs/README.md, docs/packages/{common,middleware,test-reporter}.md, the skeleton README.md, and the attributes doc URL (en/11.4/ → en/12.5/). Corrected the test-reporter event-system floor to "PHPUnit 11 or earlier".

Test plan

• vendor/bin/phpunit (PHPUnit 12.5.29) — green except env-gated cases
• vendor/bin/paratest --no-coverage — green
• test-reporter Extension smoke test → valid JSON report
• composer cs / composer stan / composer rector — clean
• CI: 8.3 + 8.4 matrix, Static Analysis, Determinism gate