Make the docs state things rather than argue them

The site read as a design journal: rationale paragraphs, hedges
("deliberately", "on purpose", "genuinely"), meta-commentary about the docs
themselves, and one em-dash every ten lines carrying an aside.

Roughly twenty rationale blocks are gone or reduced to what a reader needs
in order to use the thing. Em-dashes go from 507 to 135, and what is left is
structural rather than prose: list and definition separators, table cells,
and four inside code blocks that quote what the CLI actually prints.

Also: api.example.com becomes api.fluksio.com (the emails stay, since
bootstrap.py really defaults to admin@example.com and RFC 2606 reserves it);
the mqtt table gains the two settings it had drifted behind on and inject's
wording matches the engine; llms.txt lists the two connector pages that were
in the nav but not in it; and the two device/device_policy notes now agree.

Builds clean under `zensical build --strict`.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015YrQnKV3bnQd4K342y8tKj

docs/llms.txt

@@ -31,8 +31,10 @@
 - [The HTTP API](/code/api/): auth, flows, messages, runs, observability, websocket
 - [Remote workers](/code/workers/): fluksio-worker, device labels, artifacts across hosts
 - [Agents over MCP](/code/agents/): the tool list and the security model
+- [Writing a connector](/code/connectors/): packaging a device integration as a node type
 
 ## Reference
 - [Node types](/reference/node-types/): every built-in type and its settings
 - [Payload types](/reference/payload-types/): float, int, str, bool, json, record, list, series, artifact
 - [Configuration](/reference/configuration/): every environment variable
+- [The connector contract](/reference/connector-contract/): what a connector package must provide