feat(nav): IA restructure — every page findable, one deployments URL, an honest AI menu #5558

The owner's verdict after the wiring-level unification: "the platform navigation is not very good we need improvements." This is the structural answer.

• No more orphaned pages. The More menu becomes four labelled groups expressed as data (REPO_NAV_MORE_GROUPS, same pattern as the AI menu): Repository (Commits, Branches, Tags, Releases, Packages, Symbols, Stale branches), Planning (Milestones, Projects, Discussions, Wiki, Contributors, Moderation queue), Delivery (Gates, Merge queue, Merge checks, Deployments, Pipeline, Agents), Activity (Health report, Pulse, Push log, Traffic). Eleven formerly URL-only pages are now findable, each with a real active key — which came free, since the key union derives from the arrays. Claude sessions joined the AI menu.
• One deployments URL. /deployments is authoritative; cloud-provider runs render on it via listCloudRuns(); /cloud-deployments 301s (private-repo gate still runs first — no existence leak); all links repointed. The hand-rolled HealthNav fork is deleted; the dead duplicate /workspace registration removed with a do-not-re-add note.
• Honest AI menu. When ANTHROPIC_API_KEY is unset, the 18-item ✨ menu shows one banner ("AI features are not enabled on this instance — admins can set a key in Admin → Integrations") and mutes items rather than hiding them — their fallback pages are good.
• No page without chrome: all seven wiki pages, deployments detail, cloud-deploy settings, push log, moderation queue. Mobile: grouped panels wrap within min(92vw, 760px).
• Guards extended, not replaced: +5 data-driven describes on the existing 26-test coherence suite (group order, flat≡grouped equivalence, 301 pin, single workspace registrar via route scan, AI banner contract, wiki 7/7).

Triage kept out of nav deliberately: /coupling+/dependencies (Insights-hub cards, pinned), /timeline/:ref (file-scoped), /rollback (POST-only), /memory (demo-gated fabricated data — retirement candidate). Standing finding for a future pass: deps.tsx:467 registers a dead duplicate GET /:owner/:repo/dependencies (insights mounts first).

Re-verified at integration on current main: typecheck clean, design gate 0 banned, nav suites 54 pass.