caddy-knowledge-patch

# Caddy Knowledge Patch Baseline: Caddy through 2.8.x. Covered range: 2.9.0, 2.10.0, 2.11.1 and later 2.11 fixes, plus the `automatic-https` and `global-and-tls-options` topic batches. Use this patch when writing or reviewing Caddyfile or JSON configuration, upgrading Caddy, building custom binaries, or operating Caddy's HTTP, proxy, certificate, and telemetry features. ## Reference index | Reference | Topics | | --- | --- | | [HTTP and Caddyfile](references/http-and-caddyfile.md) | Imports, matchers, placeholders, headers, bodies, encoding, file serving, authentication, and security behavior | | [Reverse proxy](references/reverse-proxy.md) | HTTPS upstreams, health checks, retries, load balancing, transports, FastCGI, trusted proxies, and forwarding | | [Automatic HTTPS and ECH](references/automatic-https-and-ech.md) | Activation, redirects, ACME, issuers, On-Demand TLS, shared storage, local HTTPS, ECH, and wildcard selection | | [TLS and PKI](references/tls-and-pki.md) | Handshake policies, certificate selection, client authentication, trust pools, internal PKI, renewal, CA pools, and diagnostics | | [Server operations](references/server-operations.md) | Global server options, listeners, protocols, timeouts, socket activation, admin API, shutdown, storage, and runtime limits | | [Observability and extensions](references/observability-and-extensions.md) | Logs, metrics, tracing, CLI changes, build requirements, embedding, and module APIs | ## Upgrade hazards and breaki...