repro: materialize case trees, keep run.sh a thin runner

Fixtures now read directly on GitHub; the script only copies a case
into a sandbox and asserts. Case 3 reuses the case 1 tree, matching the
README table.

Author: Guria

README.md

@@ -8,11 +8,12 @@ Run:
     ./run.sh                          # uses `mise` from PATH
     MISE_BIN=/path/to/mise ./run.sh
 
-Every case runs in a throwaway HOME (`mktemp -d`); nothing touches the real
-home. Exit code 0 means every case reproduced the behavior in the table
-below — including the two conflicts. When mise gains merge semantics for
-same-target `symlink-each`, cases 1 and 3 turn into successes and `run.sh`
-starts failing: it doubles as the fix detector.
+Every case is a materialized tree under `case*/`. `run.sh` copies each into
+a throwaway sandbox (`mktemp -d`) and runs mise with an isolated HOME —
+nothing touches the real home. Exit code 0 means every case reproduced the
+behavior in the table below — including the two conflicts. When mise gains
+merge semantics for same-target `symlink-each`, cases 1 and 3 turn into
+successes and `run.sh` starts failing: it doubles as the fix detector.
 
 | case | layout | result on 2026.8.9 |
 |---|---|---|

case1-shared-target/bundles/a/config-mise/conf.d/a.toml

@@ -0,0 +1 @@
+# fragment from a

case1-shared-target/bundles/a/mise.toml

@@ -0,0 +1,2 @@
+[dotfiles]
+"~/.config/mise/" = { source = "config-mise", mode = "symlink-each" }

case1-shared-target/bundles/b/config-mise/conf.d/b.toml

@@ -0,0 +1 @@
+# fragment from b

case1-shared-target/bundles/b/mise.toml

@@ -0,0 +1,2 @@
+[dotfiles]
+"~/.config/mise/" = { source = "config-mise", mode = "symlink-each" }

case1-shared-target/mise.toml

@@ -0,0 +1,5 @@
+[settings]
+experimental = true
+
+[bootstrap]
+config_roots = ["bundles/*"]

case2-distinct-targets/bundles/a/config-mise/conf.d/a.toml

@@ -0,0 +1 @@
+# fragment from a

case2-distinct-targets/bundles/a/mise.toml

@@ -0,0 +1,2 @@
+[dotfiles]
+"~/.config/a-mine/" = { source = "config-mise", mode = "symlink-each" }

case2-distinct-targets/bundles/b/config-mise/conf.d/b.toml

@@ -0,0 +1 @@
+# fragment from b

case2-distinct-targets/bundles/b/mise.toml

@@ -0,0 +1,2 @@
+[dotfiles]
+"~/.config/b-mine/" = { source = "config-mise", mode = "symlink-each" }