Add typst-gather analyze subcommand, bump to 0.2.0

Add analyze subcommand that scans .typ files for @Preview and @Local
imports, follows transitive deps of @Local packages, and outputs
structured JSON to stdout without downloading or copying anything.

- Restructure CLI to subcommands (gather/analyze) with backwards compat
- Support reading config from stdin with `-`
- Move all println! to eprintln! so stdout is clean for JSON output
- Add AnalyzeResult/ImportInfo types with serde Serialize
- Deduplicate imports by (namespace, name, version), direct wins

Author: gordonwoodhull

Cargo.lock

@@ -1,6 +1,6 @@
 [package]
 name = "typst-gather"
-version = "0.1.3"
+version = "0.2.0"
 edition = "2021"
 repository = "https://github.com/quarto-dev/typst-gather"
 rust-version = "1.81"
@@ -10,10 +10,12 @@ typst-kit = { version = "0.14.2", features = ["packages"] }
 typst-syntax = "0.14.2"
 ecow = "0.2"
 serde = { version = "1", features = ["derive"] }
+serde_json = "1"
 clap = { version = "4", features = ["derive"] }
 toml = "0.8"
 walkdir = "2"
 globset = "0.4"
 
 [dev-dependencies]
 tempfile = "3"
+serde_json = "1"