fix(mcp): roll the dependency contracts, so the tool classes can be built - #21

* wip: consolidate tool registries (blocked on Core\Mcp contracts)

Absorbs listTools/resolve/buildDependencyGraph/call into AgentToolRegistry,
rewires McpAgentServerCommand and ToolDependencyService onto it, and deletes
Mcp\Services\ToolRegistry.

Deliberately NOT pushed. Moving the fill off $listens — the other half of the
fix — makes register() construct the tool classes, which fatals on the missing
Core\Mcp\Tools\Concerns\ValidatesDependencies trait and takes the suite from
156 failed to 1321. The registries can only usefully merge once agent consumes
dappcore/mcp and the tools become constructible.

19 tests still fail here: their fixture is a duck-typed anonymous class and the
surviving registry requires a real AgentToolInterface. Migrating them belongs
with the change that turns the server on.

* fix(mcp): one tool registry, filled at boot, read by the server

The agent MCP server advertised no tools. Three faults, each of which alone
was enough, and a green suite that noticed none of them.

Boot filled Core\Mod\Agentic\Services\AgentToolRegistry. McpAgentServerCommand
read Core\Mod\Agentic\Mcp\Services\ToolRegistry — a different class, never
bound, so Laravel handed the command a fresh empty instance on every
resolution. tools/list returned []; tools/call found nothing. Two registries
meant two answers to "what tools exist", and the server asked the one nobody
filled.

Boot filled its registry from the McpToolsRegistering event via $listens, which
ModuleScanner populates by scanning app/Core|Mod|Website. Under vendor/ that is
dead, so the event never fired and the registry it did fill was empty anyway.

And every tool class was fatal on load until #21, so even a correct
registration would have thrown on the first `new`. That one masked the other
two: nothing ever tried to construct a tool, so nothing ever failed loudly.

ToolRegistry is deleted and its capability absorbed: listTools(), resolve() and
buildDependencyGraph() return ToolMetadata built from the registered tools,
call() invokes one without the permission and dependency checks execute()
applies — kept separate because the stdio transport has no API key to check
scopes against and runs its own quota and audit passes around it. The
duplicate-name guard comes across too: two tools claiming one name is a wiring
mistake, and silently keeping the last one means the surface serves whichever
file loaded second.

The fill moves from the event into register(), the same lifecycle-independent
path used for resources, and is idempotent so a host that still delivers the
event cannot double-register.

Nineteen tests registered duck-typed anonymous classes into the loose registry.
They now implement AgentToolInterface — which they arguably always should have,
since it is the contract the tools they stand in for satisfy. One test goes
rather than being migrated: it asserted that a payload without a callable
handler is rejected, and register() is now typed, so no array can reach that
validation. There is no code path left that produces the behaviour it asserted.

Guarded against recurrence by the test that was missing all along: on a plain
booted application, registering nothing of its own, a tool constructs, the
registry is non-empty, listTools() contains plan_create, session_start and
brain_remember, and the binding is one shared instance. McpAgentServerCommandTest
passed throughout the outage because its beforeEach supplied a tool — it tested
the plumbing with a registry the test had filled, which is precisely the blind
spot.

Receipts: registry holds 40 tools after a real boot, listTools() returns the
same 40, plan_create among them. Suite 131 failed / 1193 passed, from 131 /
1190 — four guards added, one obsolete test removed, zero regressions confirmed
by diffing failing test names.

Co-Authored-By: Virgil <virgil@lethean.io>