latexgrambot: inline LaTeX bot for Telegram in Go

Renders LaTeX expressions into PNG pictures, PDF documents and native
Telegram rich text messages, entirely locally with TeX Live and poppler.

- Chat mode with /image, /pdf, /rich plus per-user preamble and DPI
- Inline mode delivering picture, PDF and rich text results
- Broad default package set preloaded into a TeX format at image build
- MongoDB persistence: settings, users, groups, render statistics
- Private S3-compatible bucket with short-lived presigned URLs
- OpenTelemetry traces over OTLP
- Kubernetes manifests and Argo CD application, Docker Compose, GitHub
  Actions CI, BSD 3-Clause license

internal/rich/rich.go

@@ -0,0 +1,28 @@
+// Package rich builds rich-message payloads for the Bot API 10.x rich
+// message endpoints (sendRichMessage and the InputRichMessageContent used in
+// inline answers). The pinned telegram-bot-api library predates the rich
+// message API, so these are plain JSON-encodable values sent through
+// api.MakeRequest.
+package rich
+
+// Message is the payload for InputRichMessage (and structurally for
+// RichMessage). Only the blocks representation is used.
+type Message struct {
+	Blocks []Block `json:"blocks"`
+}
+
+// Block is a RichBlock/InputRichBlock.
+type Block struct {
+	Type       string `json:"type"`
+	Text       any    `json:"text,omitempty"`
+	Expression string `json:"expression,omitempty"`
+	Size       int    `json:"size,omitempty"`
+}
+
+// Inline is a RichText inline node (mathematical_expression, bold, url...).
+type Inline struct {
+	Type       string `json:"type"`
+	Text       any    `json:"text,omitempty"`
+	Expression string `json:"expression,omitempty"`
+	URL        string `json:"url,omitempty"`
+}