feat: add Ctrl-R (refresh) and Ctrl-S (save-local) keybindings to model selection

[rgielen]

Summary

• Ctrl-R (refresh): Re-fetches the provider's model list from the API during any model slot dialog, without leaving the dialog. For YAML-pinned providers and under --dry-run, prints a note to stderr and stays on the current list. Any already-chosen slot value no longer in the refreshed list is reset to "(do not set)" with a stderr note.
• Ctrl-S (save toggle): Arms writing the completed selection to leitum.yaml (equivalent to --save-local). Toggles an armed state shown in the instruction footer as [save→project ON]. Unavailable (unbound, hint omitted) under --no-project-config. The dialog's final armed state fully governs the target when the dialog was shown (effective_save_local in run_claude).
• An instruction footer on every slot select advertises active shortcuts and the armed state.
• ModelSelectionResult dataclass replaces the bare dict return type of select_models.
• ResolvedModels gains save_local and dialog_shown fields (defaults keep all existing tests valid).
• PRD 03, README.md, and docs/commands.md updated to document the implemented sequential per-slot dialog design and the new keybindings.

Test plan

• ruff format, ruff check, mypy --strict, pytest all pass (178 tests, 0 failures — verified before PR open)
• 17 new unit tests cover: Ctrl-R callback invocation, not-applicable/dry-run skip, stale-value reset, callback failure fallback, Ctrl-S toggle, double toggle, initial armed state, save_local_allowed=False omits Ctrl-S, footer instruction content, effective_save_local in run_claude
• Manual smoke (real TTY, multi-model API provider): leitum claude → Ctrl-R re-fetches; Ctrl-S shows [save→project ON] and writes leitum.yaml
• Manual smoke: leitum --dry-run claude → refresh skip note, nothing written
• Manual smoke: YAML-pinned provider → "not applicable" note
• Manual smoke: leitum --no-project-config claude → no Ctrl-S hint in footer, key unbound

Closes #26

[Copilot]

Pull request overview

Adds interactive keybindings to the model-selection dialog to refresh models in-place (Ctrl‑R) and toggle saving the final selection to project config (Ctrl‑S), with corresponding plumbing through resolution/persistence and documentation updates.

Changes:

• Implement Ctrl‑R refresh and Ctrl‑S save-local toggle in select_models, including footer instructions and a structured ModelSelectionResult.
• Thread new dialog outcomes/flags through resolve_models and compute effective_save_local in run_claude.
• Add/expand unit tests and update user/PRD documentation for the sequential per-slot dialog design and keybindings.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
tests/unit/selection/test_resolver.py	Adds coverage for new ResolvedModels fields and verifies forwarding of keybinding params into the dialog.
tests/unit/selection/test_interactive_keybindings.py	New unit tests for Ctrl‑R/Ctrl‑S behavior, refresh edge cases, and footer instruction content.
tests/unit/commands/test_claude.py	Tests effective_save_local behavior (dialog-governed vs CLI-governed) and dry-run persistence behavior.
src/leitum/selection/resolver.py	Extends ResolvedModels with save_local/dialog_shown and forwards refresh/save parameters into interactive selection.
src/leitum/selection/interactive.py	Implements sentinels, keybinding injection, refresh handler, footer builder, and returns ModelSelectionResult.
src/leitum/commands/claude.py	Wires refresh callback into resolver, computes effective_save_local, and uses it in persistence + dry-run messaging.
README.md	Documents the new Ctrl‑R/Ctrl‑S shortcuts and save-local armed state indicator.
prd/03-selection-flows.md	Reconciles PRD with sequential per-slot dialog reality and documents the new keybindings and persistence resolution.
docs/commands.md	Adds command documentation describing the model-selection keybindings and footer format.

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[rgielen]

Addressed the Copilot review (commit 4104ef6).

Context: the project's actual type gate is mypy --strict src (the tests/ tree is not in the strict gate — bare mypy --strict has no target, and mypy --strict . already reports pre-existing errors in other test files on main). So none of the flagged items were breaking CI, and the new tests followed the existing loose test-file convention.

That said, the comments point at genuinely loose typing in the new tests, so I tightened them anyway:

• test_claude.py: models: dict -> models: dict[str, str] (matches the real save_project_config signature), both occurrences.
• test_interactive_keybindings.py:
  • _run_select_models return type corrected to tuple[ModelSelectionResult | None, MagicMock] (it returns a 2-tuple) and removed the stale # type: ignore[return-value].
  • chosen_so_far typed as the real dict[ModelSlot, str | None].
  • defaults typed as dict[str, Any] — note the literal Copilot suggestion (dict[str, object]) would break the Provider(**defaults) unpack under strict; Any keeps it strict-clean.

Both changed test files now pass mypy --strict individually. ruff format, ruff check, mypy --strict src, and pytest (178) all green.

[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

[rgielen]

Addressed the latest Copilot review (commit adf5918).

The point is legitimate: the other keybinding tests patch _inject_key_bindings away or mock questionary entirely, so the real Ctrl-R/Ctrl-S registration was never executed under test — a regression in binding injection could have shipped unnoticed while the footer still advertised the shortcuts.

Added TestInjectKeyBindings which drives the real function against a live prompt_toolkit.KeyBindings:

• asserts Keys.ControlR is always bound and Keys.ControlS is bound only when save_local_allowed=True (via kb.get_bindings_for_keys(...));
• asserts Keys.ControlS is absent when save_local_allowed=False;
• covers both guard paths (missing .application, non-KeyBindings object) as safe no-ops.

Suite: 178 -> 182 tests. ruff format, ruff check, mypy --strict src, and pytest all green.