refactor: clean up chatty comments and improve code maintainability

- Remove procedural comments that describe obvious code actions
- Eliminate redundant explanatory text in function documentation
- Replace repeated logger require calls with cached variables
- Fix luacheck warning about inefficient loop pattern
- Add comprehensive test coverage for edge cases and error handling
- Preserve valuable comments that explain "why" not "what"

All tests pass (215 successes) with 0 warnings/errors across 61 files.

Change-Id: I0c4a606f8508ecc98a6f4202f83bbf5b3599daf6
Signed-off-by: Thomas Kosiewski <[email protected]>

Author: ThomasK33

lua/claudecode/config.lua

@@ -17,7 +17,10 @@ M.defaults = {
   },
 }
 
---- @param config table The configuration table to validate.
+--- Validates the provided configuration table.
+-- @param config table The configuration table to validate.
+-- @return boolean true if the configuration is valid.
+-- @error string if any configuration option is invalid.
 function M.validate(config)
   assert(
     type(config.port_range) == "table"
@@ -50,7 +53,6 @@ function M.validate(config)
     "visual_demotion_delay_ms must be a non-negative number"
   )
 
-  -- Validate diff_opts
   assert(type(config.diff_opts) == "table", "diff_opts must be a table")
   assert(type(config.diff_opts.auto_close_on_accept) == "boolean", "diff_opts.auto_close_on_accept must be a boolean")
   assert(type(config.diff_opts.show_diff_stats) == "boolean", "diff_opts.show_diff_stats must be a boolean")
@@ -60,7 +62,9 @@ function M.validate(config)
   return true
 end
 
---- @param user_config table|nil The user-provided configuration table.
+--- Applies user configuration on top of default settings and validates the result.
+-- @param user_config table|nil The user-provided configuration table.
+-- @return table The final, validated configuration table.
 function M.apply(user_config)
   local config = vim.deepcopy(M.defaults)