feat: redesign desktop route flows

[ksamaschke]

Summary

• convert Workspace, Sources, Hooks, and Reports to a shared desktop master/detail shell
• keep source-management ownership in the Sources route while replacing hooks and reports dashboard-era layouts
• extract shared route primitives into desktop-master-detail.tsx and add route-flow coverage for the #217 chain

Changes

• add tests/installer/desktop-route-flow-red-phase.test.ts to pin the route-flow redesign
• rework desktop route content in InstallerDashboard.tsx around a shared two-pane shell
• add shared master/detail and selector styling in styles.css

Test Plan

• npm run build:quick
• node --test dist/tests/installer/desktop-route-flow-red-phase.test.js dist/tests/installer/desktop-shell-ux.test.js dist/tests/installer/desktop-source-route-red-phase.test.js dist/tests/installer/desktop-sidebar-routes-red-phase.test.js dist/tests/installer/desktop-settings-window-red-phase.test.js dist/tests/installer/dashboard-source-actions-style.test.js dist/tests/installer/source-management-state.test.js

Breaking Changes

• None

[ksamaschke]

ICA-REVIEW
ICA-REVIEW-RECEIPT
Reviewer-Stage: 3 (temp checkout)
Reviewer-Agent: reviewer (subagent)
PR: #256
Base: dev
Head-SHA: b64434a
Date-UTC: 2026-03-15T07:43:38Z

Findings: 0
NO FINDINGS

Checks/Tests:

• npm run build:quick (PASS)
• node --test dist/tests/installer/desktop-route-flow-red-phase.test.js dist/tests/installer/desktop-shell-ux.test.js dist/tests/installer/desktop-source-route-red-phase.test.js dist/tests/installer/desktop-sidebar-routes-red-phase.test.js dist/tests/installer/desktop-settings-window-red-phase.test.js dist/tests/installer/dashboard-source-actions-style.test.js dist/tests/installer/source-management-state.test.js (PASS)

Notes:

• Stage 3 verification executed from /tmp/ica-pr256-review-ej5wc9/repo

Result: PASS

[ksamaschke]

ICA-SECURITY-REVIEW
ICA-SECURITY-REVIEW-RECEIPT
Security-Reviewer-Stage: post-pr (temp checkout)
Security-Reviewer-Agent: security reviewer (subagent)
Security-Reviewer-Execution: dedicated-security-subagent
Security-Reviewer-Executor: github:ksamaschke
Security-Reviewer-Run-ID: sec-20260315T074339Z-b64434ad1c5d
PR: #256
Base: dev
Head-SHA: b64434a
Date-UTC: 2026-03-15T07:43:38Z

Findings: 0
NO FINDINGS

Result: PASS