[FastAPI] Modularize homepage and add side panel

This puts one more toward completion of the homepage overall; we'll need to still implement the authenticated user dashboard after this.

Signed-off-by: Kevin Morris kevr@0cost.org

Benchmarks

** Guest Homepage **
[FastAPI w/ Redis]
Benchmark #1: curl --cookie AURSID= https://localhost:8444
  Time (mean ± σ):      16.3 ms ±   5.3 ms    [User: 8.2 ms, System: 2.2 ms]
  Range (min … max):    14.5 ms …  57.2 ms    500 runs

[PHP w/ Memcached] 
Benchmark #1: curl --cookie AURSID= https://localhost:8443
  Time (mean ± σ):      64.7 ms ±   7.7 ms    [User: 8.3 ms, System: 2.3 ms]
  Range (min … max):    60.5 ms … 108.4 ms    500 runs