Support relative line number on wrapped lines (#39268)

**Problem:** Current relative line numbering creates a mismatch with
vim-style navigation when soft wrap is enabled. Users must mentally
calculate whether target lines are wrapped segments or logical lines,
making `<n>j/k` navigation unreliable and cognitively demanding.

**How things work today:**
- Real line navigation (`j/k` moves by logical lines): Requires
determining if visible lines are wrapped segments before jumping. Can't
jump to wrapped lines directly.
- Display line navigation (`j/k` moves by display rows): Line numbers
don't correspond to actual row distances for multi-line jumps.

**Proposed solution:** Count and number each display line (including
wrapped segments) for relative numbering. This creates direct
visual-to-navigational correspondence where the relative number shown
always matches the `<n>j/k` distance needed.

**Benefits:**
- Eliminates mental overhead of distinguishing wrapped vs. logical lines
- Makes relative line numbers consistently actionable regardless of wrap
state
- Preserves intuitive "what you see is what you navigate" principle
- Maintains vim workflow efficiency in narrow window scenarios

Also explained an discussed in
https://github.com/zed-industries/zed/discussions/25733.

Release Notes:

Release Notes:

- Added support for counting wrapped lines as relative lines and for
displaying line numbers for wrapped segments. Changes
`relative_line_numbers` from a boolean to an enum: `enabled`,
`disabled`, or `wrapped`.

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/migrator/src/migrations.rs

@@ -129,3 +129,9 @@ pub(crate) mod m_2025_10_17 {
 
     pub(crate) use settings::make_file_finder_include_ignored_an_enum;
 }
+
+pub(crate) mod m_2025_10_21 {
+    mod settings;
+
+    pub(crate) use settings::make_relative_line_numbers_an_enum;
+}

crates/migrator/src/migrations/m_2025_10_21/settings.rs

@@ -0,0 +1,15 @@
+use anyhow::Result;
+use serde_json::Value;
+
+pub fn make_relative_line_numbers_an_enum(value: &mut Value) -> Result<()> {
+    let Some(relative_line_numbers) = value.get_mut("relative_line_numbers") else {
+        return Ok(());
+    };
+
+    *relative_line_numbers = match relative_line_numbers {
+        Value::Bool(true) => Value::String("enabled".to_string()),
+        Value::Bool(false) => Value::String("disabled".to_string()),
+        _ => anyhow::bail!("Expected relative_line_numbers to be a boolean"),
+    };
+    Ok(())
+}

crates/migrator/src/migrator.rs

@@ -214,6 +214,7 @@ pub fn migrate_settings(text: &str) -> Result<Option<String>> {
         ),
         MigrationType::Json(migrations::m_2025_10_16::restore_code_actions_on_format),
         MigrationType::Json(migrations::m_2025_10_17::make_file_finder_include_ignored_an_enum),
+        MigrationType::Json(migrations::m_2025_10_21::make_relative_line_numbers_an_enum),
     ];
     run_migrations(text, migrations)
 }