feat(phase2-E): multi-provider routing via secutools delegation

Adds optional delegation of agent-queue tasks to the SecuAAS secutools
AI platform (GPU / Gemini / Claude API) instead of dispatching to a
local Claude Code tmux session. Per-task opt-in via YAML frontmatter
fields preferred_ai, allow_delegation, complexity_hint — absence keeps
the Phase 1 behaviour exactly (zero breaking change).

Go side:
- internal/secutools: HTTP client with exponential-backoff retries
  (SubmitJob/GetJob/WaitForResult), DecideProvider map adapter for CLI
  use, table tests.
- internal/router: struct-typed Decide() with strict precedence
  (needs_claude_code > preferred_ai=claude-code > allow_delegation=false
  > preferred_ai > fail-safe local on unknown).
- internal/delegation: Manager submits jobs, writes .md.delegated
  markers for on-restart recovery, runs a periodic reaper that moves
  completed jobs into done/ with provider/cost footer and failed jobs
  into failed/.
- internal/dispatcher: WithDelegation() opt-in, routeTask hook before
  findFreeSession, skips .md.delegated in assignNextTask.
- internal/api: /api/delegated/status (active jobs + counters),
  /watchdog/status extended with delegation counters.
- cmd/ccl-delegate: small CLI exposing submit/get/result/decide so the
  bash dispatcher can call the same contract without duplicating logic.
- cmd/claude-failover: delegation wired opt-in via SECUTOOLS_API_KEY.

Tests:
- 29+ new unit tests across router, secutools, delegation, dispatcher,
  api packages. go test -race -count=1 clean.
- tests/phase2-E-integration.sh: bash end-to-end against a Python
  stdlib mock HTTP server, exercising the dev-management scripts.

Forward-compat with watchdog (Phase 1 B1 already ignores
state=delegated_to_secutools) so delegated tasks aren't flagged stale.

go.mod

@@ -2,9 +2,9 @@ module forge.secuaas.ovh/olivier/claude-failover
 
 go 1.22
 
-require gopkg.in/yaml.v3 v3.0.1
-
 require (
-	github.com/fsnotify/fsnotify v1.9.0 // indirect
-	golang.org/x/sys v0.13.0 // indirect
+	github.com/fsnotify/fsnotify v1.9.0
+	gopkg.in/yaml.v3 v3.0.1
 )
+
+require golang.org/x/sys v0.13.0 // indirect