refactor(git): gitlog as gitlog:// URI singleton, fix synthetic-URI cwd resolve

lua/git/object.lua

@@ -182,7 +182,11 @@ function M.read_uri(buf)
     vim.b[buf].git_worktree = worktree
 
     vim.bo[buf].swapfile = false
-    vim.bo[buf].bufhidden = "wipe"
+    -- `unload` frees content when the buffer is hidden, but keeps the
+    -- bufnr in the buffer list so the jumplist's `(bufnr, line, col)`
+    -- entries stay valid. `<C-o>` back to a hidden URI buffer triggers
+    -- the BufReadCmd again, refreshing content via `cat-file -p`.
+    vim.bo[buf].bufhidden = "unload"
 
     ---@type string?
     local stdout = pending_content[buf]
@@ -228,6 +232,9 @@ function M.read_uri(buf)
     end
 
     if stdout then
+        -- Reload paths (`:e`, `<C-o>` to an unloaded buf) re-enter
+        -- with `modifiable = false` from the prior load.
+        vim.bo[buf].modifiable = true
         vim.api.nvim_buf_set_lines(buf, 0, -1, false, util.split_lines(stdout))
     end