infra(nvim): add stylua formatter + prek hook; normalize heph.nvim Lua

A `.stylua.toml` (Spaces/2, else stylua defaults) + a `stylua-system`
prek hook make Lua whitespace formatter-enforced (the repo had no Lua
formatter, so style was hand-maintained and drifted). Normalized the
three non-conformant files in passing. 21 nvim e2e specs still green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

heph.nvim/lua/heph/init.lua

@@ -30,10 +30,7 @@ function M.setup(opts)
     rpc.call("health", {})
   end)
   if not ok then
-    require("heph.util").notify(
-      "no hephd at " .. cfg.socket .. " — run `heph daemon start`",
-      vim.log.levels.WARN
-    )
+    require("heph.util").notify("no hephd at " .. cfg.socket .. " — run `heph daemon start`", vim.log.levels.WARN)
   end
 
   config.apply_keymaps(cfg)

heph.nvim/tests/e2e/capture_spec.lua

@@ -34,10 +34,7 @@ describe("task capture to done", function()
     vim.api.nvim_win_set_cursor(0, { 2, 0 })
     require("heph.view").open_under_cursor()
     local ctxbuf = vim.api.nvim_get_current_buf()
-    assert.are.equal(
-      "heph://node/" .. ranked[1].canonical_context_id,
-      vim.api.nvim_buf_get_name(ctxbuf)
-    )
+    assert.are.equal("heph://node/" .. ranked[1].canonical_context_id, vim.api.nvim_buf_get_name(ctxbuf))
 
     -- Add a checklist item and save.
     vim.api.nvim_buf_set_lines(ctxbuf, 0, -1, false, { "- [ ] buy shingles" })

heph.nvim/tests/e2e/helpers.lua

@@ -79,11 +79,16 @@ end
 --- tests of the no-daemon-running case). `rm` removes it.
 function M.tmp()
   local dir = unique_dir()
-  return { dir = dir, sock = dir .. "/s", db = dir .. "/db", rm = function()
-    pcall(function()
-      vim.fn.delete(dir, "rf")
-    end)
-  end }
+  return {
+    dir = dir,
+    sock = dir .. "/s",
+    db = dir .. "/db",
+    rm = function()
+      pcall(function()
+        vim.fn.delete(dir, "rf")
+      end)
+    end,
+  }
 end
 
 --- Start a daemon on explicit paths and bind the plugin's rpc to it. Returns a
@@ -91,10 +96,7 @@ end
 function M.start_on(dir, sock, db)
   assert(#sock < 104, "socket path too long for sun_path: " .. sock)
   local bin = M.hephd_bin()
-  assert(
-    vim.fn.executable(bin) == 1,
-    "hephd not built/executable: " .. bin .. "  (run: cargo build -p hephd)"
-  )
+  assert(vim.fn.executable(bin) == 1, "hephd not built/executable: " .. bin .. "  (run: cargo build -p hephd)")
 
   local exited = { done = false }
   local d = spawn({