Problem

When the code indexer runs at startup (tokio::spawn in agent_setup.rs), the user sees no progress feedback. For a typical Zeph workspace (~571 indexable files, ~410 Rust sources), each file requires an embedding call to the LLM provider — this can take 30–120 seconds total. During this time:

• CLI mode: silent, nothing is shown
• TUI mode: no spinner, no status label — only a log line tracing::info!("project indexed") appears at the very end

The user has no idea whether indexing is still running or how far along it is.

Analysis

The current flow in indexer.rs (index_project()):

1. Walks the file tree, collects entries: Vec<_> — total count is known upfront (total = entries.len())
2. Iterates with for (i, entry) in entries.iter().enumerate() — both i and total are available at every step
3. Only emits tracing::info!(progress = "{i+1}/{total}") — no channel to surface this to the UI

All the data needed for a progress display is already there — it just isn't surfaced to the caller.

Proposed solution

1. Add a progress channel to IndexerConfig

pub struct IndexProgress {
    pub files_done: usize,
    pub files_total: usize,
    pub chunks_created: usize,
}

Add progress_tx: Option<tokio::sync::watch::Sender<IndexProgress>> to IndexerConfig.
Send an update inside the loop after each file is processed.

2. CLI mode: print progress to the channel

In agent_setup.rs, after spawning the background task, send a system message:

⚙ Indexing codebase in the background (571 files) — you can start chatting now.

On completion:

✓ Codebase indexed: 410 files, 4823 chunks (42s) — code search is ready.

3. TUI mode: show spinner + counter in the status bar

Wire the watch::Receiver<IndexProgress> into App:

• During indexing: ⠸ Indexing codebase… 127/571 files (22%)
• On completion: ✓ Index ready (571 files, 4823 chunks) shown for 3s, then cleared

The TUI already has status_label: Option<String> and a spinner — minimal wiring needed.

Scope

• crates/zeph-index/src/indexer.rs — add IndexProgress struct, send updates via watch::Sender after each file
• src/agent_setup.rs — create the channel, pass sender to indexer, emit start/done messages
• crates/zeph-tui/src/app.rs — receive IndexProgress and render in status bar
• crates/zeph-channels/src/cli.rs or agent startup — emit start/done system messages in CLI mode

Acceptance criteria

• Progress counter is visible in both CLI and TUI modes during background indexing
• TUI status bar shows N/M files (X%) updated after each file
• Completion message includes: files indexed, chunks created, total duration
• No blocking — user can interact while indexing runs in the background
• No performance regression from progress update overhead