feat: v0.7.0 — configuration post-install : bloc config: par agent (env_map + fichiers), adaptateurs TOML/YAML/JSON/key=value, édition douce, jamais de token en clair (api_key = @secret) (closes #91)

- Nouveau module src/agent_config.rs : apply_post_install (écriture fichiers), apply_env_map (env injectée au start/run), provider_pref (provider > config.provider_default > default_provider)
- am install écrit les fichiers de config de l'agent avec le provider/modèle résolus ; --no-config / install.configurable:false / --dry-run respectés ; agent sans adaptateur → message clair, install réussit
- Catalogue : blocs config: pour claude-code, codex, agentty (+ provider_default)

src/config.rs

@@ -342,6 +342,9 @@ pub struct AgentDef {
     /// provider's default_model when unset.
     #[serde(default)]
     pub model: Option<String>,
+    /// Post-install provider configuration: env_map + files (issue #91).
+    #[serde(default)]
+    pub config: Option<AgentConfig>,
     #[serde(default)]
     pub tags: Vec<String>,
     /// When false, the agent is listed but cannot be installed locally.
@@ -616,6 +619,33 @@ impl InstallSpec {
     }
 }
 
+/// Post-install provider configuration of an agent (issue #91): the env vars
+/// the agent expects and the config files to write or softly edit. The
+/// api_key slot is always injected as the `@secret` reference (issue #89) —
+/// a token is never written in clear.
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+#[serde(default)]
+pub struct AgentConfig {
+    /// Expected env vars, keyed by semantic slot (api_key / model /
+    /// base_url / provider) -> the agent's variable name.
+    pub env_map: BTreeMap<String, String>,
+    /// Configuration files to write or softly edit after the install.
+    pub files: Vec<AgentConfigFile>,
+    /// Provider of this agent, otherwise settings.default_provider.
+    pub provider_default: Option<String>,
+}
+
+/// One config file of an agent (issue #91).
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub struct AgentConfigFile {
+    /// File path (supports ~ and env vars).
+    pub path: String,
+    /// Keys to write among: api_key, model, base_url, provider.
+    #[serde(default)]
+    pub keys: Vec<String>,
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 #[serde(deny_unknown_fields)]
 pub struct Dependency {