feat(v2): M6 Dependency Manager, multi-dependency wake-up

Implements M6: dependency_manager.v tracks a table of node
descriptors (node_id/state/required_dependencies/resolved_
dependencies/producer_ids -- §10's exact field list), incrementing a
waiting node's resolved count whenever one of its listed producers
completes, transitioning it to READY once resolved==required, and
dispatching ready nodes to the Neural Director (M5) one at a time via
a backpressure-safe valid/ready interface.

Verified with Verilator on a small hand-built DAG: node0/node1 have no
dependencies (dispatch immediately); node2 depends on BOTH node0 AND
node1 ("dipendenze multiple") and stays WAITING until both complete,
confirmed via an explicit negative check after only one resolves;
node3 depends on node0 ALONE, demonstrating a single producer
("node0") satisfying two different consumers' dependencies
("risultati condivisi... piu' consumer") -- node3 fully, node2
partially. 4/4 tests pass.

Scope for this milestone (decisions.log DEC-0008): dependency
COUNTING/readiness only, no direct producer-to-consumer value
forwarding (§11 frames that as a "quando possibile" optimization, not
a correctness requirement -- deferred until real bandwidth
measurements justify it) and no node-slot reclamation after dispatch
(not exercised by any scenario built so far).

Real synthesis: 0 CHECK problems, 763 LUT4/474 FF/0 DSP/0 CCU2C. Real
place&route (module fits the TRELLIS_IO budget as a bare top-level
this time, no harness needed): Fmax 155.30 MHz, PASS at 80MHz.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v

hardware/v2/docs/ROADMAP.md

@@ -31,8 +31,11 @@ reali, non solo scritto).
       first-free. 4/4 test PASS (dispatch + coda + backpressure reale
       su N_SLOTS=2). FSM ridotta a 4 stati, dependency rimandata a M6
       (`logs/decisions.log` DEC-0007). Fmax 250.50 MHz.
-- [ ] **M6 — Dependency Manager** (`dependency_manager.v`), ready/waiting
-      queue, dependency counters, wake-up, producer tracking.
+- [x] **M6 — Dependency Manager** (`dependency_manager.v`), ready/waiting
+      queue, dependency counters, wake-up, producer tracking. 4/4 test
+      PASS (dipendenze multiple + produttore condiviso/piu' consumer).
+      Fmax 155.30 MHz. Forwarding di valori e riuso slot rimandati
+      (`logs/decisions.log` DEC-0008).
 - [ ] **M7 — Dataflow Core** (`dataflow_core.v`), integrazione completa.
 - [ ] **M8 — PSRAM integration**, controller V1 non modificato, misura reale.
 - [ ] **M9 — Full benchmark**, tabella V1 vs V2 (§32 del mandato).