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/Cargo.toml

@@ -0,0 +1,34 @@
+[package]
+name = "idx-core"
+description = "Data layer for Indonesian stock market (IDX) market, financial, and ownership data"
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+license.workspace = true
+repository.workspace = true
+homepage.workspace = true
+readme = "../../README.md"
+keywords = ["idx", "stocks", "indonesia", "finance"]
+categories = ["finance"]
+include = ["/Cargo.toml", "/LICENSE", "/src/**", "/tests/fixtures/**"]
+
+[features]
+default = ["ownership"]
+ownership = ["dep:rusqlite", "dep:quick-xml", "dep:sha2", "dep:zip"]
+# Derives clap::ValueEnum on enums frontends expose as CLI arguments.
+clap = ["dep:clap"]
+
+[dependencies]
+clap = { workspace = true, optional = true }
+ureq.workspace = true
+serde.workspace = true
+serde_json.workspace = true
+toml.workspace = true
+directories = "5"
+chrono.workspace = true
+thiserror = "2"
+fastrand = "2"
+rusqlite = { workspace = true, optional = true }
+quick-xml = { version = "0.37", optional = true }
+sha2 = { workspace = true, optional = true }
+zip = { workspace = true, optional = true }