Sidebar Re-design: Routing

[cstns]

Replace hardcoded router link paths with named routes, reorganize vue router and small styling adjustments

Description

• replaced hardcoded router link paths with named routes
• reorganized routes in order to correctly handle router-link active property and consistent behavior across page navigation and hierarchy

Related Issue(s)

part of #4673

Checklist

• I have read the contribution guidelines
• Suitable unit/system level tests have been added and they pass
• Documentation has been updated
  • Upgrade instructions
  • Configuration details
  • Concepts
• Changes flowforge.yml?
  • Issue/PR raised on FlowFuse/helm to update ConfigMap Template
  • Issue/PR raised on FlowFuse/CloudProject to update values for Staging/Production

Labels

• Includes a DB migration? -> add the area:migration label

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.79%. Comparing base (1cd6d0f) to head (eb09846).
Report is 6 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4744   +/-   ##
=======================================
  Coverage   78.79%   78.79%           
=======================================
  Files         311      311           
  Lines       14781    14781           
  Branches     3384     3384           
=======================================
  Hits        11646    11646           
  Misses       3135     3135           

Flag	Coverage Δ
backend	78.79% <ø> (ø)

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[cstns]

Do not merge until #4743 passes review