fix(lsp): return config table from after/lsp specs (Neovim 0.12)

[venkatarenduchintala]

Problem

Neovim startup crashes (issue #36):

Failed to run `config` for mason-lspconfig.nvim
.../after/lsp/ansiblels.lua: not a table
  vim/lsp.lua:347 __index → vim/lsp.lua:617 enable
  → mason-lspconfig automatic_enable → mason.lua:19

On Neovim 0.12 the vim.lsp.config[name] getter re-sources after/lsp/<name>.lua and requires it to return a table. The specs used the imperative setter form vim.lsp.config('name', {...}), which returns nil — so when mason-lspconfig's automatic_enable calls vim.lsp.enable(name) (→ the getter), it throws not a table and aborts startup.

Fix

Convert all eight after/lsp/*.lua specs to the declarative return { ... } form (the documented Neovim 0.11+ native pattern). gopls, lua_ls, rust_analyzer, helm_ls, yamlls, ansiblels, jsonnet_ls, eslint.

eslint keeps its EslintFixAll-on-save autocmd, now registered under a clear = true augroup so re-sourcing during config resolution stays idempotent.

Validation

Ran against nvim v0.12.2 (the version in the report):

• luac -p clean on all 8 files.
• Each file now returns a table with its settings (and jsonnet_ls its cmd).
• vim.lsp.config[name] — the exact failing frame — resolves for all 8 servers with settings merged, no throw (previously threw for ansiblels).

Fixes #36.