feat(bins): multi-library populate_knowledge + progress UX

populate_knowledge now loads real libraries from the DB instead of
fabricating a single library_id=1 row from BASE_PATH. Adds --library
<id|name> to restrict the walk and validates --path against the selected
library roots. The full library set is still passed to InsightGenerator so
resolve_full_path can probe every root when an insight resolves to a
different library than the one being walked.

Adds indicatif progress bars across the long-running utility binaries via
a shared src/bin_progress.rs helper (determinate bar + open-ended spinner
with consistent styling). Per-batch info! noise is replaced by the bar's
throughput/ETA; warnings and errors route through pb.println so they
scroll above the bar instead of fighting with it.

  populate_knowledge   spinner during scan, determinate bar over all libs
  backfill_hashes      spinner with running hashed/missing/errors counts
  import_calendar      determinate bar; embedding/store failures inline
  import_location_*    determinate bar advancing by chunk size
  import_search_*      determinate bar; pb cloned into the spawn task
  cleanup_files P1     determinate bar over DB paths
  cleanup_files P2     determinate bar; pb.suspend() around y/n/a/s prompt

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/bin_progress.rs

@@ -0,0 +1,34 @@
+//! Shared progress-bar styling for the utility binaries. Centralised so every
+//! `cargo run --bin ...` tool gets the same look and feel.
+
+use indicatif::{ProgressBar, ProgressStyle};
+
+const DETERMINATE_TEMPLATE: &str = "{spinner:.green} [{elapsed_precise}] [{wide_bar:.cyan/blue}] \
+     {human_pos}/{human_len} ({percent}%) {per_sec} eta {eta} {msg}";
+
+const SPINNER_TEMPLATE: &str = "{spinner:.green} [{elapsed_precise}] {human_pos} {per_sec} {msg}";
+
+/// Determinate progress bar used when the total work is known up front.
+pub fn determinate(total: u64, message: impl Into<String>) -> ProgressBar {
+    let pb = ProgressBar::new(total);
+    pb.set_style(
+        ProgressStyle::with_template(DETERMINATE_TEMPLATE)
+            .expect("hard-coded template parses")
+            .progress_chars("=> "),
+    );
+    pb.set_message(message.into());
+    pb
+}
+
+/// Spinner used for open-ended work (e.g. paginated DB scans that loop until
+/// empty). Throughput is shown via `{per_sec}`; tick at a steady cadence so
+/// it animates even when work is bursty.
+pub fn spinner(message: impl Into<String>) -> ProgressBar {
+    let pb = ProgressBar::new_spinner();
+    pb.set_style(
+        ProgressStyle::with_template(SPINNER_TEMPLATE).expect("hard-coded template parses"),
+    );
+    pb.set_message(message.into());
+    pb.enable_steady_tick(std::time::Duration::from_millis(120));
+    pb
+}