- Use sync.Pool for relay buffers instead of stack-allocated arrays.
  A [16379]byte on the goroutine stack forces Go to grow it to 32KB
  (next power of two). Pooled buffers keep goroutine stacks small.

- Same fix for doppelganger write buffer ([16384]byte in conn.start).

- Replace idle goroutines with context.AfterFunc in proxy.ServeConn
  and relay.Relay. These goroutines existed only to wait on ctx.Done()
  and close connections. AfterFunc achieves the same without allocating
  a goroutine until the context is actually cancelled.

Net effect: at 3000 concurrent connections on a 1-vCPU/961MB VPS,
the unmodified binary drops 246 connections and falls to 10 MB/s.
With these changes: zero failures, 63 MB/s, 31% lower RSS.

Closes #412

Add dynamic cert noise calibration for FakeTLS handshake

Instead of a separate cert_probe.go that duplicates the scout's TLS
connection logic, measure the cert chain size directly from the same
HTTPS connections the scout already makes.

Changes:
- Extend ScoutConnResult with payloadLen field
- Add Write interception to ScoutConn for handshake boundary detection
- Scout.learn() now computes cert size (sum of ApplicationData between
  CCS and first client Write) alongside inter-record durations
- Ganger aggregates cert sizes across raids and exposes NoiseParams()
  via atomic pointer for lock-free reads from proxy goroutines
- Proxy reads NoiseParams from Ganger on each handshake instead of
  probing at startup
- Remove cert_probe.go, disk cache, and related config options
  (noise-cache-path, noise-cache-ttl, noise-probe-count)

Falls back to legacy 2500-4700 range until the first scout raid
completes (typically within 1-2 seconds of startup).

The hardcoded noise range (2500-4700 bytes) in the FakeTLS ServerHello
does not match the real certificate chain sizes of many popular fronting
domains (e.g., dl.google.com ≈ 6480 bytes, microsoft.com ≈ 13004 bytes).
This makes the proxy detectable by DPI systems that compare the
ApplicationData size with the real cert chain size for the SNI domain.

On startup, probe the fronting domain's actual TLS handshake size and
use the measured value ± jitter instead of the static range. Falls back
to the legacy 2500-4700 range if the probe fails.

Also adds optional caching of probe results between restarts
(noise-cache-path, noise-cache-ttl) and a configurable probe count
(noise-probe-count) under [defense.doppelganger].

Closes #408

Update stale codeql configuration

Update PGO

Fix build with profiling

Allow using directory bind mounts for a docker container

This helps with a situation when some applications do not allow mounting
individual files, but whole directories. In that case users could mount
`/config` directory with a single file, `config.toml`: `-v
/path/to/dir:/config`. Also, there is a backward compatibility to using
a single `/config.toml`

Add more architectures for mtg

Document a necessety of increasing limits for systemd unit

Add PGO

It seems that default DynamicUser limits are very low. We have to
increase them anyway.

Avoid double buffering in TLS hot path

Optimize waiting time for TLS chunker

Show ip of telegram endpoints in event stream

Fix flaky test

fix: ensure network.Dial and MakeHTTPClient use socks5 proxy

The package `network/v2/proxy_network.go` does not wrap `network.Dial`
and `network.MakeHTTPClient`, which causes them to bypass the SOCKS5
proxy and initiate TCP connections directly from the local machine.

Fix preferIPOnlyIPv6