test: add comprehensive test suite for adrs-core

- Add 67 unit tests for types module with test_case and proptest
- Add 32 unit tests for config module (load, save, roundtrip)
- Add 69 unit tests for parsing (legacy and frontmatter formats)
- Add 40 unit tests for template rendering (Nygard, MADR, custom)
- Add 40 unit tests for repository operations
- Add 15 adr-tools compatibility tests
- Add proptest property-based tests for slug and filename generation
- Fix unicode handling in slug function (use is_ascii_alphanumeric)
- Add support for adr-tools typo 'superceded' in status/link parsing
- Total: 244 tests passing

Author: joshrotenberg

Cargo.lock

@@ -47,6 +47,8 @@ assert_cmd = "2"
 assert_fs = "1"
 predicates = "3"
 tempfile = "3"
+proptest = "1"
+test-case = "3"
 
 # The profile that 'dist' will build with
 [profile.dist]

Cargo.toml

@@ -22,3 +22,5 @@ regex.workspace = true
 
 [dev-dependencies]
 tempfile.workspace = true
+proptest.workspace = true
+test-case.workspace = true

crates/adrs-core/Cargo.toml

@@ -0,0 +1,7 @@
+# Seeds for failure cases proptest has generated in the past. It is
+# automatically read and these particular cases re-run before any
+# novel cases are generated.
+#
+# It is recommended to check this file in to source control so that
+# everyone who runs the test benefits from these saved cases.
+cc 2ee7bcbf9310a86d6dd2d776dedf508f73563df70af09aa93972bafe6dcfbeb4 # shrinks to s = "ꫛ"