feat(cli): Implement complete command-line interface

Provides a user-friendly CLI for all GitLab Inbox operations.

src/cli/mod.rs - Clap command definitions:
- Global --config flag for alternate config path
- Subcommands: init, auth-test, doctor, version, backup, reset,
  migrate, sync-status, ingest, list, count, show
- Ingest supports --type (issues/merge_requests), --project filter,
  --force lock override, --full resync
- List supports rich filtering: --state, --author, --assignee,
  --label, --milestone, --since, --due-before, --has-due-date
- List supports --sort (updated/created/iid), --order (asc/desc)
- List supports --open to launch browser, --json for scripting

src/cli/commands/ - Command implementations:

init.rs: Interactive configuration wizard
- Prompts for GitLab URL, token env var, projects to track
- Creates config file and initializes database
- Supports --force overwrite and --non-interactive mode

auth_test.rs: Verify GitLab authentication
- Calls /api/v4/user to validate token
- Displays username and GitLab instance URL

doctor.rs: Environment health check
- Validates config file exists and parses correctly
- Checks database connectivity and migration state
- Verifies GitLab authentication
- Reports token environment variable status
- Supports --json output for CI integration

ingest.rs: Data synchronization from GitLab
- Acquires sync lock with stale detection
- Shows progress bars for issues and discussions
- Reports sync statistics on completion
- Supports --full flag to reset cursors and refetch all data

list.rs: Query local database
- Formatted table output with comfy-table
- Filters build dynamic SQL with parameterized queries
- Username filters normalize @ prefix automatically
- --open flag uses 'open' crate for cross-platform browser launch
- --json outputs array of issue objects

show.rs: Detailed entity view
- Displays issue metadata in structured format
- Shows full description with markdown
- Lists labels, assignees, milestone
- Shows discussion threads with notes

count.rs: Entity statistics
- Counts issues, discussions, or notes
- Supports --type filter for discussions/notes

sync_status.rs: Display sync watermarks
- Shows last sync time per project
- Displays cursor positions for debugging

src/main.rs - Application entry point:
- Initializes tracing subscriber with env-filter
- Parses CLI arguments via clap
- Dispatches to appropriate command handler
- Consistent error formatting for all failure modes

src/lib.rs - Library entry point:
- Exports cli, core, gitlab, ingestion modules
- Re-exports Config, GiError, Result for convenience

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/cli/mod.rs

@@ -0,0 +1,168 @@
+//! CLI module with clap command definitions.
+
+pub mod commands;
+
+use clap::{Parser, Subcommand};
+
+/// GitLab Inbox - Unified notification management
+#[derive(Parser)]
+#[command(name = "gi")]
+#[command(version, about, long_about = None)]
+pub struct Cli {
+    /// Path to config file
+    #[arg(short, long, global = true)]
+    pub config: Option<String>,
+
+    #[command(subcommand)]
+    pub command: Commands,
+}
+
+#[derive(Subcommand)]
+pub enum Commands {
+    /// Initialize configuration and database
+    Init {
+        /// Skip overwrite confirmation
+        #[arg(long)]
+        force: bool,
+
+        /// Fail if prompts would be shown
+        #[arg(long)]
+        non_interactive: bool,
+    },
+
+    /// Verify GitLab authentication
+    AuthTest,
+
+    /// Check environment health
+    Doctor {
+        /// Output as JSON
+        #[arg(long)]
+        json: bool,
+    },
+
+    /// Show version information
+    Version,
+
+    /// Create timestamped database backup
+    Backup,
+
+    /// Delete database and reset all state
+    Reset {
+        /// Skip confirmation prompt
+        #[arg(long)]
+        confirm: bool,
+    },
+
+    /// Run pending database migrations
+    Migrate,
+
+    /// Show sync state
+    SyncStatus,
+
+    /// Ingest data from GitLab
+    Ingest {
+        /// Resource type to ingest
+        #[arg(long, value_parser = ["issues", "merge_requests"])]
+        r#type: String,
+
+        /// Filter to single project
+        #[arg(long)]
+        project: Option<String>,
+
+        /// Override stale sync lock
+        #[arg(long)]
+        force: bool,
+
+        /// Full re-sync: reset cursors and fetch all data from scratch
+        #[arg(long)]
+        full: bool,
+    },
+
+    /// List issues or MRs from local database
+    List {
+        /// Entity type to list
+        #[arg(value_parser = ["issues", "mrs"])]
+        entity: String,
+
+        /// Maximum results
+        #[arg(long, default_value = "50")]
+        limit: usize,
+
+        /// Filter by project path
+        #[arg(long)]
+        project: Option<String>,
+
+        /// Filter by state
+        #[arg(long, value_parser = ["opened", "closed", "all"])]
+        state: Option<String>,
+
+        /// Filter by author username
+        #[arg(long)]
+        author: Option<String>,
+
+        /// Filter by assignee username
+        #[arg(long)]
+        assignee: Option<String>,
+
+        /// Filter by label (repeatable, AND logic)
+        #[arg(long)]
+        label: Option<Vec<String>>,
+
+        /// Filter by milestone title
+        #[arg(long)]
+        milestone: Option<String>,
+
+        /// Filter by time (7d, 2w, 1m, or YYYY-MM-DD)
+        #[arg(long)]
+        since: Option<String>,
+
+        /// Filter by due date (before this date, YYYY-MM-DD)
+        #[arg(long)]
+        due_before: Option<String>,
+
+        /// Show only issues with a due date
+        #[arg(long)]
+        has_due_date: bool,
+
+        /// Sort field
+        #[arg(long, value_parser = ["updated", "created", "iid"], default_value = "updated")]
+        sort: String,
+
+        /// Sort order
+        #[arg(long, value_parser = ["desc", "asc"], default_value = "desc")]
+        order: String,
+
+        /// Open first matching issue in browser
+        #[arg(long)]
+        open: bool,
+
+        /// Output as JSON
+        #[arg(long)]
+        json: bool,
+    },
+
+    /// Count entities in local database
+    Count {
+        /// Entity type to count
+        #[arg(value_parser = ["issues", "mrs", "discussions", "notes"])]
+        entity: String,
+
+        /// Filter by noteable type (for discussions/notes)
+        #[arg(long, value_parser = ["issue", "mr"])]
+        r#type: Option<String>,
+    },
+
+    /// Show detailed entity information
+    Show {
+        /// Entity type to show
+        #[arg(value_parser = ["issue", "mr"])]
+        entity: String,
+
+        /// Entity IID
+        iid: i64,
+
+        /// Filter by project path (required if iid is ambiguous)
+        #[arg(long)]
+        project: Option<String>,
+    },
+}