refactor: split into idx-core library and idx-cli binary workspace

Phase 2 of docs/DESIGN.md, no behavior change:

- crates/idx-core (library): api, analysis, cache, config file handling
  and provider selection, curl_impersonate, error, ownership, runtime,
  plus the shared test fixtures. clap derives are behind an optional
  `clap` feature so the library does not require clap.
- crates/idx-cli (binary `idx`): cli/, output/, and IdxConfig (output
  format and color resolution). Package and binary names are unchanged.
- config.rs is split: file read/write and validation move to core; a
  CLI test keeps core's OUTPUT_VALUES in sync with OutputSetting.
- ownership::db::open_db/db_path drop their unused IdxConfig argument.
- One workspace version; shared dependency versions; no third-party
  version changes in Cargo.lock. LICENSE is symlinked into each crate.
- flake: workspace version, new source paths, and a per-crate package
  check (idx-cli is built from its tarball against packaged idx-core,
  since idx-core is not on crates.io yet). CI cache key, release path
  filter, and the golden whitespace-hook exclusion follow the new layout.

Parity: all 143 golden outputs match byte for byte without
regeneration; 157 core + 17 CLI unit tests (173 before plus the new
OUTPUT_VALUES sync test), 62 CLI tests pass. Live A/B against main:
16/16 stocks cases identical; ownership discover got IDX 403 on both
(exit 4 vs 1 is the phase 1 exit-code change).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/idx-core/src/lib.rs

@@ -0,0 +1,39 @@
+//! idx-core: retrieval and analysis of Indonesian (IDX) market, financial, and
+//! investor data, shared by the `idx` CLI and other frontends.
+//! See docs/DESIGN.md.
+
+pub mod analysis;
+pub mod api;
+pub mod cache;
+pub mod config;
+pub mod curl_impersonate;
+pub mod error;
+#[cfg(feature = "ownership")]
+pub mod ownership;
+
+pub mod runtime {
+    use std::fmt::Display;
+    use std::sync::atomic::{AtomicBool, Ordering};
+
+    static QUIET: AtomicBool = AtomicBool::new(false);
+
+    pub fn set_quiet(quiet: bool) {
+        QUIET.store(quiet, Ordering::Relaxed);
+    }
+
+    pub fn is_quiet() -> bool {
+        QUIET.load(Ordering::Relaxed)
+    }
+
+    pub fn info(message: impl Display) {
+        if !is_quiet() {
+            eprintln!("info: {message}");
+        }
+    }
+
+    pub fn warn(message: impl Display) {
+        if !is_quiet() {
+            eprintln!("warning: {message}");
+        }
+    }
+}