refactor(web): remove dead src/types/navigation.ts InspectorTab, fold into utils/inspectorTabs

[cliffhall]

Summary

clients/web/src/types/navigation.ts exports InspectorTab, a tab-identifier union that has zero references anywhere in the repo (including tests). It duplicates — and drifts from — the live type in src/utils/inspectorTabs.ts.

Surfaced during the #1776 review (PR #1784) while auditing the new src/lib vs src/utils rule.

The two competing types

// src/types/navigation.ts  — 0 importers (dead)
export type InspectorTab = "tools" | "apps" | "prompts" | "resources" | "logs" | "tasks" | "protocol";

// src/utils/inspectorTabs.ts — the one actually used (App.tsx, lib/oauthResume.ts, …)
export const INSPECTOR_TAB_IDS = ["Apps","Tools","Prompts","Resources","Tasks","Logs","Protocol","Network"] as const;
export type InspectorTabId = (typeof INSPECTOR_TAB_IDS)[number];

They differ in case (lowercase vs capitalized) and membership (navigation.ts is missing Network), and the dead one is the stale copy.

Proposed change

• Delete src/types/navigation.ts (the InspectorTab type is dead).
• The live tab-identifier type stays InspectorTabId in src/utils/inspectorTabs.ts — no fold needed unless a lowercase-spelled variant is wanted, in which case derive it there.
• After removal, src/types/ holds only the ambient react-syntax-highlighter .d.ts stubs (wired via tsconfig.app.json paths), which makes the refactor(web): sharpen the src/lib vs src/utils rule and move misfiled modules #1776 "no domain types in src/types/" framing exactly true.

Notes

Kept out of PR #1784 deliberately — deleting exported symbols changes the coverage denominator and is a scope change from that PR's pure-move mandate. Behavior-preserving (the type has no consumers).

Acceptance

• src/types/navigation.ts removed; InspectorTab gone.
• No dangling references (there are none today; verify after).
• npm run ci green.

[cliffhall]

Fixed in #1792 (merged to v2/main).