[Schema][Server] Add top-level title to Tool (#288)

* feat(schema): add top-level title to Tool

Mirror PR #278's Prompt change for Tool:

- Add optional ?string $title to Mcp\Schema\Tool between $name
  and $inputSchema. fromArray() now reads $data['title'];
  jsonSerialize() emits 'title' right after 'name'. The
  @phpstan-type ToolData gains title?: string.
- Add ?string $title to the #[McpTool] attribute between $name
  and $description.
- Note ToolAnnotations::$title as deprecated-for-display in
  favor of Tool::$title per MCP spec 2025-06-18 (PHPDoc only,
  field retained for BC).

Phase 1 of plan 01--tool-title-spec-compliance. Later phases
update Discoverer, Builder::addTool(), ArrayLoader, and the
conformance fixture to match the new signature.

* feat(server): thread title through discovery

- Discoverer::processMethod() now propagates McpTool::$title
  into every discovered Tool via named arguments.
- Builder::addTool() accepts ?string $title between $name and
  $description. [BC Break] positional callers passing the old
  $description as 3rd positional argument must switch to named
  arguments, matching the precedent set for addPrompt() in
  0.5.0.
- tests/Conformance/server.php migrated to named-argument form
  for every addTool() call.

Phase 2 of plan 01--tool-title-spec-compliance.

* feat(loader): forward title in ArrayLoader

ArrayLoader now reads 'title' from each tool config entry and
passes it into the Tool constructor, completing the wiring
from Builder::addTool() through array-driven registration.

The $tools @param array-shape typedef gains title: ?string
between name and description.

Phase 3 of plan 01--tool-title-spec-compliance.

* test(schema): cover Tool.title end-to-end

- New tests/Unit/Schema/ToolTest.php: constructor round-trip,
  jsonSerialize key-order when title set vs null, fromArray
  tolerance.
- New tests/Unit/Capability/Discovery/DiscovererToolTitleTest
  plus a TitleFixture class verifying McpTool(title: ...)
  propagates through discovery into the registered Tool.
- New tests/Unit/Capability/Registry/Loader/ArrayLoader...
  test verifying array-driven title propagation.
- Extend McpToolTest for title named-arg and default-null.
- Extend BuilderTest with addTool(title: 't') propagation.
- Update tests/Unit/.../RegistryTest, CallToolHandlerTest,
  ListToolsHandlerTest and examples/.../server.php
  new Tool(...) call sites to pass title (named args) so
  they match the new constructor signature.
- CHANGELOG 0.6.0 section: feature bullet + [BC Break]
  note for addTool() signature, mirroring 0.5.0 Prompt
  entries.
- docs/server-builder.md: addTool() row and prose now
  list title? between name and description.

Phase 4 of plan 01--tool-title-spec-compliance. All 730
phpunit tests pass; remaining phpstan warnings are
pre-existing and unrelated to Tool.title.

* refactor(schema): make Tool.title non-BC-breaking

Move `title` to the end of the Tool, Builder::addTool, and McpTool
attribute constructors with a default of null. This preserves
positional-argument compatibility and removes the need for
`title: null` boilerplate at call sites. JSON serialization order
(name, title, inputSchema, ...) is unchanged.

Also tighten the new tests: parameterize ToolTest with data
providers, fold the Discoverer title fixture into the existing
DiscoverableToolHandler, and drop the reflection-heavy Builder
test that overlapped with ArrayLoaderToolTitleTest.

* fix: move title after name

---------

Co-authored-by: DDEV User <nobody@example.com>

chore(http): create constant for session id header (#246)

make static methods in Error final (#204)

[Server][Conformance] Kicking off adoption of conformance testing (#181)

make sure StdioTransport does not break BC for 0.2.1 (#201)

* make sure StdioTransport does not break BC for 0.2.1

* fix phpstan baseline

Add changelog for 0.2.0 (#187)

Make logger nullable in Transport constructors (#152)

- BaseTransport: Accept ?LoggerInterface parameter and convert null to NullLogger
- StdioTransport: Change logger parameter to nullable
- StreamableHttpTransport: Change logger parameter to nullable
- InMemoryTransport: Fix missing parent::__construct() call and add logging