feat(config): add /config TUI with tab-based settings and plugin config framework

- textual-based ConfigApp with General, Plugins, and per-plugin tabs
- GeneralConfig (user_name, assistant_name) + plugin_settings dict added to PyraConfig
- ConfigField dataclass and config_fields() method added to plugin protocol
- /config slash command in chat REPL launches the TUI
- pyra auto-runs setup wizard on first invocation when no config.yaml exists
- CLAUDE.md updated with config_fields() plugin guide and Code Inventory entries

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/pyra/plugins/base.py

@@ -1,12 +1,22 @@
 from __future__ import annotations
 
-from dataclasses import dataclass
+from dataclasses import dataclass, field
 from typing import TYPE_CHECKING, Any, Callable, Coroutine, Protocol, runtime_checkable
 
 if TYPE_CHECKING:
     from rich.console import Console
 
 
+@dataclass
+class ConfigField:
+    key: str           # key in plugin_settings[name] dict
+    label: str         # display label in the config TUI
+    type: str          # "text" | "bool" | "select"
+    default: Any = ""
+    options: list[str] = field(default_factory=list)  # for "select" type
+    description: str = ""                              # optional hint shown below the field
+
+
 @dataclass
 class Tool:
     name: str
@@ -35,6 +45,7 @@ class PyraPlugin(Protocol):
     def agent_spec(self) -> AgentSpec | None: ...
     def setup(self, console: Console, vault_writer: Callable[[str, str], None]) -> None: ...
     def daemon_tasks(self) -> list[Coroutine]: ...  # type: ignore[type-arg]
+    def config_fields(self) -> list[ConfigField]: ...
 
 
 class BasePlugin:
@@ -64,3 +75,6 @@ class BasePlugin:
 
     def daemon_tasks(self) -> list[Coroutine]:  # type: ignore[type-arg]
         return []
+
+    def config_fields(self) -> list[ConfigField]:
+        return []