feat(lint): resolve linters discovery-first

Resolve linter_deps through the shared resolver against nvim-lint's registry,
batched per filetype off the lint events, with an idle-gated 120s parity sweep
(generation-guarded) for never-opened filetypes and a fallback timer so an
already-idle session isn't stranded. The plugin-loading buffer gets its initial
lint. Late configures re-lint only the new linter; a broken-linter verdict is
memoized so its load-time side effects run once. ftdetect/github.lua detects
GitHub workflow files as yaml.github (consumed by the actionlint/shuck run:
linters here, and claimed by the LSP servers).

Author: charliie-dev

ftdetect/github.lua

@@ -0,0 +1,12 @@
+-- GitHub Actions workflow files get the dotted filetype so their dedicated
+-- tooling keys on it: nvim-lint's `yaml.github` linters (actionlint + shuck)
+-- and the LSP filetype claims in servers/yamlls.lua / servers/gh_actions_ls.lua.
+-- Deliberately unanchored, same shape as ftdetect/gitlab.lua: an explicit `$`
+-- (any variant) empirically stops vim.filetype.match from ever matching the
+-- pattern on this nvim, so suffixed copies (ci.yml.bak) re-type too — accepted
+-- parity with the gitlab precedent.
+vim.filetype.add({
+	pattern = {
+		[".*/%.github/workflows/.*%.ya?ml"] = "yaml.github",
+	},
+})