docs(config): clarify profile names and make examples copy-paste safe

Rename the size-numbered profiles so the digits read as parameter count,
not Qwen version: qwen35 -> qwen35b (llama.cpp.config.example, build_archive
smoke test, SECURITY_AND_OPERATIONS.md) and qwen27 -> qwen27b
(llama.cpp.config).

Drop the misleading `--profile qwen35` from the README/man/install examples:
that profile only exists in the .example file, so pasted commands failed
against the real config. Primary examples now omit --profile (using the
[default] section, which always resolves), with one example plus a note
showing how to select a real [model.<name>] profile.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

build_archive.py

@@ -335,7 +335,7 @@ def smoke_test_install(output_path: Path) -> None:
                 str(llamacppctl_bin),
                 "--print-effective-config",
                 "--config", str(config_example),
-                "--profile", "qwen35",
+                "--profile", "qwen35b",
                 "--start",
                 "--dry-run",
             ],