refactor(dap): simplify hover tree rendering architecture

- Add row/column tracking to Content for multi-line highlight support
- Switch from Node:format() returning Content to Node:format_into(content)
- Remove complex highlight offset calculations and manual text merging
- Use content:current_line() instead of tracking line_number in nodes
- Fix pointer child formatting to use item.name directly
- Clean up unused imports and simplify render_node method

lua/ow/dap/hover/content.lua

@@ -1,5 +1,4 @@
 -- Highlighted text content builder for DAP tree display
-local log = require("ow.log")
 ---@class ow.dap.hover.content.Capture
 ---@field start_col integer
 ---@field end_col integer
@@ -9,12 +8,15 @@ local log = require("ow.log")
 
 ---@class ow.dap.hover.Highlight
 ---@field group string Highlight group name
+---@field start_row integer Start line (0-indexed)
 ---@field start_col integer Start column (0-indexed)
+---@field end_row integer End line (0-indexed)
 ---@field end_col integer End column (0-indexed)
 
 ---@class ow.dap.hover.Content
 ---@field text string The complete text content
 ---@field highlights ow.dap.hover.Highlight[] List of highlights to apply
+---@field _current_row integer Current line position (for building)
 ---@field _current_col integer Current column position (for building)
 local Content = {}
 Content.__index = Content
@@ -25,15 +27,23 @@ function Content.new()
     return setmetatable({
         text = "",
         highlights = {},
+        _current_row = 0,
         _current_col = 0,
     }, Content)
 end
 
+---@return integer
+function Content:current_line()
+    return self._current_row + 1
+end
+
 ---Add text with optional highlighting
----@param text string Text to add
+---@param text string Text to add. May not contain line breaks.
 ---@param highlight_group? string Optional highlight group
 function Content:add(text, highlight_group)
+    local start_row = self._current_row
     local start_col = self._current_col
+    local end_row = self._current_row
     local end_col = start_col + #text
 
     self.text = self.text .. text
@@ -42,16 +52,19 @@ function Content:add(text, highlight_group)
     if highlight_group then
         table.insert(self.highlights, {
             group = highlight_group,
+            start_row = start_row,
             start_col = start_col,
+            end_row = end_row,
             end_col = end_col,
         })
     end
 end
 
 ---Add text with tree-sitter syntax highlighting
----@param text string The text to highlight
----@param lang string Language for tree-sitter
+---@param text string Text to add. May not contain line breaks.
+---@param lang string Language for tree-sitter highlighting
 function Content:add_with_treesitter(text, lang)
+    local start_row = self._current_row
     local start_col = self._current_col
 
     -- First, just add the text normally
@@ -76,22 +89,23 @@ function Content:add_with_treesitter(text, lang)
     -- Add highlights for all captures (overlapping is fine)
     for id, node in query:iter_captures(tree:root(), text, 0, -1) do
         local capture_name = query.captures[id]
-        local start_row, start_col_rel, end_row, end_col_rel = node:range()
+        local start_row_rel, start_col_rel, end_row_rel, end_col_rel =
+            node:range()
 
-        -- TODO: keep track of text as lines instead, so we can handle multiline
-        --       highlights
-        if start_row == end_row then -- Single line only
-            -- Convert to absolute column positions
-            local abs_start_col = start_col + start_col_rel
-            local abs_end_col = start_col + end_col_rel
+        -- Convert to absolute positions
+        local abs_start_row = start_row + start_row_rel
+        local abs_end_row = start_row + end_row_rel
+        local abs_start_col = start_col + start_col_rel
+        local abs_end_col = start_col + end_col_rel
 
-            -- Add the highlight
-            table.insert(self.highlights, {
-                group = "@" .. capture_name,
-                start_col = abs_start_col,
-                end_col = abs_end_col,
-            })
-        end
+        -- Add the highlight
+        table.insert(self.highlights, {
+            group = "@" .. capture_name,
+            start_row = abs_start_row,
+            start_col = abs_start_col,
+            end_row = abs_end_row,
+            end_col = abs_end_col,
+        })
     end
 end
 
@@ -99,6 +113,7 @@ end
 function Content:newline()
     self:add("\n")
     self._current_col = 0
+    self._current_row = self._current_row + 1
 end
 
 ---Get the lines as a table
@@ -110,35 +125,14 @@ end
 ---Apply highlights to a buffer
 ---@param ns_id integer
 ---@param buf integer Buffer handle
----@param line_offset? integer Line offset to apply highlights at (default 0)
-function Content:apply_highlights(ns_id, buf, line_offset)
-    line_offset = line_offset or 0
-    local lines = self:get_lines()
-    local current_line = 0
-    local line_start_col = 0
-
+function Content:apply_highlights(ns_id, buf)
     for _, highlight in ipairs(self.highlights) do
-        -- Find which line this highlight belongs to
-        while
-            current_line < #lines - 1
-            and highlight.start_col
-                >= line_start_col + #lines[current_line + 1] + 1
-        do
-            line_start_col = line_start_col + #lines[current_line + 1] + 1 -- +1 for newline
-            current_line = current_line + 1
-        end
-
-        -- Calculate column positions relative to line start
-        local start_col = highlight.start_col - line_start_col
-        local end_col = highlight.end_col - line_start_col
-
-        -- Apply highlight
         vim.hl.range(
             buf,
             ns_id,
             highlight.group,
-            { line_offset + current_line, start_col },
-            { line_offset + current_line, end_col }
+            { highlight.start_row, highlight.start_col },
+            { highlight.end_row, highlight.end_col }
         )
     end
 end