Merge master into the Gemini and Antigravity branch

Both sides rewrote the doctor: master rebuilt it around ready flags so a
fully local setup stops reading as broken, while this branch taught it
that Google has a key of its own and that the local model has neither a
key nor a program. Kept master's structure and folded the branch in: the
two hosted providers answer for their keys, a CLI for its program, and
the JSON keeps both the provider-aware "key" and master's "ready".

SECRET_KEYS gained groq on master and gemini here; the resolution keeps
all four. _conclude was also changed by both: master stopped matching
stderr wording and asks _API_TROUBLE instead, this branch renamed its
last parameter to the provider's short name so a session is stored under
the name it is read back by; the rename now rides on master's body.
codex_models() and the settings loaders landed beside the new Gemini
ones, so both stay. The new cleanup tests called the CLI fake by its old
name, fake_run, which master had renamed to fake_cli.

README.md

@@ -142,7 +142,8 @@ set next to it.
 
 An indicator in the screen corner shows a red dot, a live waveform and the
 elapsed time, then the stage it is on. It never takes focus. Pressing
-`Ctrl+Space` again while Dikte is still working does nothing; nothing queues up.
+`Ctrl+Space` again while the last dictation is still being cleaned up starts
+the next one; it is transcribed and pasted in turn, behind the one still going.
 A dictation and a command to the agent do wait on each other for the microphone,
 which is one device, but for nothing else: each has its own indicator, and the
 second one stacks above the first while both are up.