[ty] Add note to unresolved-import hinting to users to configure their Python environment

crates/ty/tests/cli.rs

@@ -296,6 +296,7 @@ fn cli_arguments_are_relative_to_the_current_directory() -> anyhow::Result<()> {
     3 |
     4 | stat = add(10, 15)
       |
+    info: make sure your Python environment is properly configured: https://github.com/astral-sh/ty/blob/main/docs/README.md#python-environment
     info: rule `unresolved-import` is enabled by default
 
     Found 1 diagnostic
@@ -481,6 +482,7 @@ fn cli_rule_severity() -> anyhow::Result<()> {
     3 |
     4 | y = 4 / 0
       |
+    info: make sure your Python environment is properly configured: https://github.com/astral-sh/ty/blob/main/docs/README.md#python-environment
     info: rule `unresolved-import` is enabled by default
 
     error[division-by-zero]: Cannot divide object of type `Literal[4]` by zero
@@ -532,6 +534,7 @@ fn cli_rule_severity() -> anyhow::Result<()> {
     3 |
     4 | y = 4 / 0
       |
+    info: make sure your Python environment is properly configured: https://github.com/astral-sh/ty/blob/main/docs/README.md#python-environment
     info: rule `unresolved-import` was selected on the command line
 
     warning[division-by-zero]: Cannot divide object of type `Literal[4]` by zero
@@ -1120,6 +1123,7 @@ fn check_specific_paths() -> anyhow::Result<()> {
     3 |
     4 | print(z)
       |
+    info: make sure your Python environment is properly configured: https://github.com/astral-sh/ty/blob/main/docs/README.md#python-environment
     info: rule `unresolved-import` is enabled by default
 
     error[unresolved-import]: Cannot resolve imported module `does_not_exist`
@@ -1128,6 +1132,7 @@ fn check_specific_paths() -> anyhow::Result<()> {
     2 | import does_not_exist  # error: unresolved-import
       |        ^^^^^^^^^^^^^^
       |
+    info: make sure your Python environment is properly configured: https://github.com/astral-sh/ty/blob/main/docs/README.md#python-environment
     info: rule `unresolved-import` is enabled by default
 
     Found 3 diagnostics
@@ -1153,6 +1158,7 @@ fn check_specific_paths() -> anyhow::Result<()> {
     3 |
     4 | print(z)
       |
+    info: make sure your Python environment is properly configured: https://github.com/astral-sh/ty/blob/main/docs/README.md#python-environment
     info: rule `unresolved-import` is enabled by default
 
     error[unresolved-import]: Cannot resolve imported module `does_not_exist`
@@ -1161,6 +1167,7 @@ fn check_specific_paths() -> anyhow::Result<()> {
     2 | import does_not_exist  # error: unresolved-import
       |        ^^^^^^^^^^^^^^
       |
+    info: make sure your Python environment is properly configured: https://github.com/astral-sh/ty/blob/main/docs/README.md#python-environment
     info: rule `unresolved-import` is enabled by default
 
     Found 2 diagnostics

crates/ty_python_semantic/resources/mdtest/snapshots/basic.md_-_Structures_-_Multiple_objects_imp…_(cbfbf5ff94e6e104).snap

@@ -26,6 +26,7 @@ error[unresolved-import]: Cannot resolve imported module `does_not_exist`
 2 | from does_not_exist import foo, bar, baz
   |      ^^^^^^^^^^^^^^
   |
+info: make sure your Python environment is properly configured: https://github.com/astral-sh/ty/blob/main/docs/README.md#python-environment
 info: rule `unresolved-import` is enabled by default
 
 ```

crates/ty_python_semantic/resources/mdtest/snapshots/basic.md_-_Structures_-_Unresolvable_module_…_(846453deaca1071c).snap

@@ -24,6 +24,7 @@ error[unresolved-import]: Cannot resolve imported module `zqzqzqzqzqzqzq`
 1 | import zqzqzqzqzqzqzq  # error: [unresolved-import] "Cannot resolve imported module `zqzqzqzqzqzqzq`"
   |        ^^^^^^^^^^^^^^
   |
+info: make sure your Python environment is properly configured: https://github.com/astral-sh/ty/blob/main/docs/README.md#python-environment
 info: rule `unresolved-import` is enabled by default
 
 ```

crates/ty_python_semantic/resources/mdtest/snapshots/basic.md_-_Structures_-_Unresolvable_submodu…_(4fad4be9778578b7).snap

@@ -36,6 +36,7 @@ error[unresolved-import]: Cannot resolve imported module `a.foo`
 3 |
 4 | # Topmost component unresolvable:
   |
+info: make sure your Python environment is properly configured: https://github.com/astral-sh/ty/blob/main/docs/README.md#python-environment
 info: rule `unresolved-import` is enabled by default
 
 ```
@@ -48,6 +49,7 @@ error[unresolved-import]: Cannot resolve imported module `b.foo`
 5 | import b.foo  # error: [unresolved-import] "Cannot resolve imported module `b.foo`"
   |        ^^^^^
   |
+info: make sure your Python environment is properly configured: https://github.com/astral-sh/ty/blob/main/docs/README.md#python-environment
 info: rule `unresolved-import` is enabled by default
 
 ```

crates/ty_python_semantic/resources/mdtest/snapshots/unresolved_import.md_-_Unresolved_import_di…_-_An_unresolvable_impo…_(72d090df51ea97b8).snap

@@ -28,6 +28,7 @@ error[unresolved-import]: Cannot resolve imported module `does_not_exist`
 2 |
 3 | x = does_not_exist.foo
   |
+info: make sure your Python environment is properly configured: https://github.com/astral-sh/ty/blob/main/docs/README.md#python-environment
 info: rule `unresolved-import` is enabled by default
 
 ```

crates/ty_python_semantic/resources/mdtest/snapshots/unresolved_import.md_-_Unresolved_import_di…_-_Using_`from`_with_an…_(9fa713dfa17cc404).snap

@@ -28,6 +28,7 @@ error[unresolved-import]: Cannot resolve imported module `does_not_exist`
 2 |
 3 | stat = add(10, 15)
   |
+info: make sure your Python environment is properly configured: https://github.com/astral-sh/ty/blob/main/docs/README.md#python-environment
 info: rule `unresolved-import` is enabled by default
 
 ```

crates/ty_python_semantic/src/types/infer.rs

@@ -3812,11 +3812,16 @@ impl<'db> TypeInferenceBuilder<'db> {
         let Some(builder) = self.context.report_lint(&UNRESOLVED_IMPORT, range) else {
             return;
         };
-        builder.into_diagnostic(format_args!(
+        let mut diagnostic = builder.into_diagnostic(format_args!(
             "Cannot resolve imported module `{}{}`",
             ".".repeat(level as usize),
             module.unwrap_or_default()
         ));
+        if level == 0 {
+            diagnostic.info(
+                "make sure your Python environment is properly configured: https://github.com/astral-sh/ty/blob/main/docs/README.md#python-environment"
+            );
+        }
     }
 
     fn infer_import_definition(