Page that shows how Zeronet is utilizing resource limits (connections/threads/sockets)

ISSUE:
For some users ZeroNet is slow, possibly not optimaly utilizing computer resources due to its settings or is not effective quickly downloading optional files. Noob does not know how to fix it and eventually stop using Zeronet due to lag.
PS: the lag may be also due to [ZN using single CPU thread?](https://github.com/HelloZeroNet/ZeroNet/issues/2312)

SOLUTION:
/Stats, /Config or /Performance page may contain an overview of how particular configuration variables are utilized (number of connections/threads, sockets and such):

```
--threads_fs_read THREADS_FS_READ
Number of threads for file read operations (default:
1)
--threads_fs_write THREADS_FS_WRITE
Number of threads for file write operations (default:
1)
--threads_crypt THREADS_CRYPT
Number of threads for cryptographic operations
(default: 2)
--threads_db THREADS_DB
Number of threads for database operations (default: 1)
--connected_limit connected_limit
Max connected peer per site (default: 8)
--global_connected_limit global_connected_limit
Max connections (default: 512)
--workers workers Download workers per site (default: 5)
--max_files_opened limit
Change maximum opened files allowed by OS to this
value on startup (default: 2048)
```

and also based on operating system limits show where are the reserves so the noob user knows how to tweak zeronet configuration variables (maybe do actual change by clicking the button/submitting the value right on the page)

Next to each value, Zeronet may show current usage, average usage and maximum seen usage.

ZN should proactively warn if some value is maxed out and link to this configuration page.

For better understanding, later may be added an enhancement where user click particular value to see the details (maybe even real-time? or with a refresh button). For example click "connected_limit" to see the list of top 3 sites with highest conn. limit count. Click "threads_fs_write" to see the count and the list of files to which is being writen by which zeronet task.

I think in overal it would be beneficial for users to better underatand ZN configuration variables and set these appropriately.

Start by checking the existing /Stats, /Config, and /Performance entry points, if present, and trace how the listed resource limits are configured. Define a focused first version that reports current, average, and maximum usage and identifies what constitutes a maxed-out value; the broader editing, real-time details, and per-site or per-file views remain later enhancements.

索引モデルが issue の本文から書いたものです。