feat(cli): wire defaultProject through init and all commands

Integrates the defaultProject config field across the entire CLI
surface so that omitting `-p` now falls back to the configured default.

Init command:
- New `--default-project` flag on `lore init` (and robot-mode variant)
- InitInputs.default_project: Option<String> passed through to run_init
- Validation in run_init ensures the default matches a configured path
- Interactive mode: when multiple projects are configured, prompts
  whether to set a default and which project to use
- Robot mode: InitOutputJson now includes default_project (omitted when
  null) for downstream automation
- Autocorrect dictionary updated with `--default-project`

Command handlers applying effective_project():
- handle_issues: list filters use config default when -p omitted
- handle_mrs: same cascading resolution for MR listing
- handle_ingest: dry-run and full sync respect the default
- handle_timeline: TimelineParams.project resolved via effective_project
- handle_search: SearchCliFilters.project resolved via effective_project
- handle_generate_docs: project filter cascades
- handle_who: falls back to config.default_project when -p omitted
- handle_count: both count subcommands respect the default
- handle_discussions: discussion count filters respect the default

Robot-docs:
- init command schema updated with --default-project flag and
  response_schema showing default_project as string?
- New config_notes section documents the defaultProject field with
  type, description, and example

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

src/cli/commands/init.rs

@@ -10,6 +10,7 @@ pub struct InitInputs {
     pub gitlab_url: String,
     pub token_env_var: String,
     pub project_paths: Vec<String>,
+    pub default_project: Option<String>,
 }
 
 pub struct InitOptions {
@@ -23,6 +24,7 @@ pub struct InitResult {
     pub data_dir: String,
     pub user: UserInfo,
     pub projects: Vec<ProjectInfo>,
+    pub default_project: Option<String>,
 }
 
 pub struct UserInfo {
@@ -104,6 +106,20 @@ pub async fn run_init(inputs: InitInputs, options: InitOptions) -> Result<InitRe
         ));
     }
 
+    // Validate default_project matches one of the configured project paths
+    if let Some(ref dp) = inputs.default_project {
+        let matched = inputs.project_paths.iter().any(|p| {
+            p.eq_ignore_ascii_case(dp)
+                || p.to_ascii_lowercase()
+                    .ends_with(&format!("/{}", dp.to_ascii_lowercase()))
+        });
+        if !matched {
+            return Err(LoreError::Other(format!(
+                "defaultProject '{dp}' does not match any configured project path"
+            )));
+        }
+    }
+
     if let Some(parent) = config_path.parent() {
         fs::create_dir_all(parent)?;
     }
@@ -118,6 +134,7 @@ pub async fn run_init(inputs: InitInputs, options: InitOptions) -> Result<InitRe
             .iter()
             .map(|p| ProjectConfig { path: p.clone() })
             .collect(),
+        default_project: inputs.default_project.clone(),
     };
 
     let config_json = serde_json::to_string_pretty(&config)?;
@@ -152,5 +169,6 @@ pub async fn run_init(inputs: InitInputs, options: InitOptions) -> Result<InitRe
         data_dir: data_dir.display().to_string(),
         user,
         projects: validated_projects.into_iter().map(|(p, _)| p).collect(),
+        default_project: inputs.default_project,
     })
 }