build: modernize repository (#27)

* build: clean up gitignore and remove empty gitmodules

Problem: .gitignore contained 48 lines of C/shared-object boilerplate
irrelevant to a Lua Neovim plugin. .gitmodules was tracked but empty.

Solution: replace .gitignore with minimal entries covering only files
this project actually produces. Delete the vestigial .gitmodules.

* build: add editorconfig and prettierrc

Problem: no editor or formatter configuration, inconsistent with
cp.nvim and diffs.nvim conventions.

Solution: add .editorconfig (2-space Lua indent, utf-8, final newline)
and .prettierrc (prose wrap, 80 cols, single quotes, no semi) matching
the other repos.

* build: add Makefile for lint and test targets

Problem: .github/pre-commit calls `make fastlint` and .github/pre-push
calls `make lint && make test`, but no Makefile existed, so the git
hooks failed.

Solution: add Makefile with lint (stylua + selene), fastlint
(pre-commit), and test (luarocks test) targets.

* docs: add fork copyright to LICENSE

Problem: LICENSE only contained the original author's copyright notice.

Solution: add a second copyright line for the fork maintainer. MIT
requires retaining the original notice; adding a line for derivative
work is standard practice.

* ci: restructure workflows to quality/test/luarocks pattern

Problem: CI used a single tests.yml for linting, typechecking, and
testing. No conditional path filtering, no markdown format check, and
a stale mirror_upstream_prs.yml and duplicate luarocks.yml existed.

Solution: replace tests.yml with quality.yaml (stylua, selene,
lua-typecheck, prettier with dorny/paths-filter) and test.yaml
(nvim-busted, stable+nightly matrix). Update luarocks.yaml to
reference quality.yaml. Delete mirror_upstream_prs.yml and duplicate
luarocks.yml. Fix automation workflow sender check.

* build: rewrite issue templates

Problem: issue templates used upstream stevearc references, severity
dropdowns, outdated lazy.nvim bootstrap, and the .yml extension
inconsistent with other repos.

Solution: replace with .yaml templates matching cp.nvim/diffs.nvim
style. Bug report uses prerequisites checkboxes, checkhealth output,
modern lazy.nvim bootstrap with vim.g.oil pattern. Feature request
uses problem/solution/alternatives format. Add config.yaml to disable
blank issues and link discussions.

* docs: rewrite README

Problem: README contained upstream triage tables, severity dropdowns,
the old setup() pattern, a tree view question, and references to
stevearc/oil.nvim as the primary source.

Solution: full rewrite matching cp.nvim/diffs.nvim style with bold
tagline, features list, requirements, installation, documentation,
FAQ (lazy.nvim setup with vim.g.oil, migration guide, alternatives),
and acknowledgements crediting the original author.

* revert: remove Makefile

Problem: Makefile was added in b9279b5 but was previously deleted
intentionally.

Solution: remove it.

.gitignore

@@ -1,47 +1,12 @@
-# Compiled Lua sources
-luac.out
-
-# luarocks build files
-*.src.rock
-*.zip
-*.tar.gz
-
-# Object files
-*.o
-*.os
-*.ko
-*.obj
-*.elf
-
-# Precompiled Headers
-*.gch
-*.pch
-
-# Libraries
-*.lib
-*.a
-*.la
-*.lo
-*.def
-*.exp
-
-# Shared objects (inc. Windows DLLs)
-*.dll
-*.so
-*.so.*
-*.dylib
-
-# Executables
-*.exe
-*.out
-*.app
-*.i*86
-*.x86_64
-*.hex
-
+doc/tags
+*.log
+.*cache*
+CLAUDE.md
+.claude/
+node_modules/
 .direnv/
 .envrc
-doc/tags
-scripts/benchmark.nvim
+venv/
 perf/tmp/
+scripts/benchmark.nvim
 profile.json