feat(tui): Phase 3 power features — Who, Search, Timeline, Trace, File History screens

Complete TUI Phase 3 implementation with all 5 power feature screens:

- Who screen: 5 modes (expert/workload/reviews/active/overlap) with
  mode tabs, input bar, result rendering, and hint bar
- Search screen: full-text search with result list and scoring display
- Timeline screen: chronological event feed with time-relative display
- Trace screen: file provenance chains with expand/collapse, rename
  tracking, and linked issues/discussions
- File History screen: per-file MR timeline with rename chain display
  and discussion snippets

Also includes:
- Command palette overlay (fuzzy search)
- Bootstrap screen (initial sync flow)
- Action layer split from monolithic action.rs to per-screen modules
- Entity and render cache infrastructure
- Shared who_types module in core crate
- All screens wired into view/mod.rs dispatch
- 597 tests passing, clippy clean (pedantic + nursery), fmt clean

.liquid-mail.toml

@@ -0,0 +1,13 @@
+# Liquid Mail config (TOML)
+#
+# Prefer env vars for secrets:
+#   LIQUID_MAIL_HONCHO_API_KEY
+#   LIQUID_MAIL_HONCHO_WORKSPACE_ID
+#
+[honcho]
+api_key = "hch-v3-pmx23gk9k60xlqffpxpyjj8pywnxkpjkic9bdygx21iydvyxbeialioz5ehhcp1r"
+# workspace_id is optional.
+# If omitted, Liquid Mail defaults it to the repo name (git root folder name).
+# Honcho uses get-or-create semantics for workspaces, so it will be created on first use.
+# workspace_id = "my-repo"
+base_url = "https://api.honcho.dev"