feat(alias): keep text formatting, name kinds in /aliases, copyable commands

Text and caption formatting now survives an alias. Bold, italic, code, links
and mentions are stored as entities beside the text and sent back with it, on
the /insert, bare-command and inline paths alike. This works because the text
is re-sent byte-identical, so the offsets the entities carry stay valid — the
earlier comment claiming otherwise was wrong. They go back as entities rather
than re-rendered markup, which avoids escaping and re-parsing content the user
never wrote as markup.

/aliases now lists one line per name with what it holds, so the list says what
each will send:

    3 aliases:
    /cheer — sticker
    /clip — video
    /greeting — text

That costs one store read per listed alias, since DocStore has no bulk get and
the kind lives in the document. The reads stop once the message is full, so the
cost is bounded by what fits in one reply rather than by how many aliases exist.

Every reply that names a command or an alias wraps it in <code>, so tapping it
copies something ready to send. The generic usage lines stay plain text: they
contain a literal <name> placeholder that HTML mode would swallow as a tag.

Replying to another bot's message gets its own refusal. Telegram delivers that
reply with the content stripped, so capture finds nothing and the format advice
read as if the wrong kind had been sent. Checked only after capture fails, so
this bot's own messages — which are readable — never reach it.

docs/aliases.md

@@ -133,20 +133,40 @@ single call, while naming each kind would cost one read per alias — a round tr
 each against MongoDB, on a dispatcher that serves one update at a time. To find
 out what a name holds, `/insert` it.
 
-Names list in their folded (lowercase) form, which is exactly what `/insert`
-takes, and each is wrapped in a `<code>` span so tapping one copies just that
-name.
+One line per alias, showing what the name holds, with the invocation in a
+`<code>` span so tapping it copies a command ready to send:
 
-The list is trimmed to fit Telegram's 4096-character message limit and ends
-with `…and N more.` when it does not fit; the count at the top is always the
-true total. The trim budget counts the markup, not only the names — at 13 bytes
-a pair the tags outweigh a short name.
+```
+3 aliases:
+/cheer — sticker
+/clip — video
+/greeting — text
+```
+
+Names list in their folded (lowercase) form, which is exactly what `/insert`
+takes.
+
+This costs one store read per *listed* alias — `DocStore` has no bulk get and
+the kind lives in the document. The reads stop as soon as the message is full,
+so the cost is bounded by what fits in one reply rather than by how many
+aliases exist. The list is trimmed to Telegram's 4096-character limit and ends
+with `…and N more.`; the count at the top is always the true total.
 
 ## Behaviour worth knowing
 
-**Text loses its formatting.** Bold, links and mentions are stored as plain
-text: re-sending entities means carrying offsets that no longer line up once the
-text is repeated in a different message. A bare URL still auto-links.
+**Formatting survives.** Bold, italic, code, links and mentions are stored as
+entities alongside the text, and captions keep theirs too. This works because
+the text is re-sent byte-identical: entity offsets are relative to that text,
+so they stay valid. They are sent back as entities rather than re-rendered as
+markup, which avoids escaping and re-parsing content the user never wrote as
+markup.
+
+**Another bot's message cannot be saved.** Telegram's own rule: *"Bots will not
+be able to see messages from other bots regardless of mode."* The reply arrives
+with its content stripped, so there is nothing to store and no setting that
+would change it. `/alias` says so specifically rather than implying the format
+was unsupported. Forwarding the message to yourself first and aliasing your own
+copy works.
 
 **A `file_id` can stop working** — the original file was deleted, or Telegram
 rejects it. `/insert` answers with something actionable rather than a generic