fix(gen_srcs): skip unnecessary load symbols

[miridius]

Depends on #85.

Problem

gen_srcs always emits load("@rules_clojure//:rules.bzl", "clojure_library", "clojure_test") in every BUILD file, even when:

1. There are no clojure_test targets — the "clojure_test" symbol is loaded but never used.
2. The directory has no .clj files at all — the entire load() statement is unnecessary.

Solution

Two changes to gen-dir, both derived from a single pass over the rules ns-rules emits — has-binary? and has-tests? come from the same reduce (= :clojure_binary :type, = :clojure_test :type). No re-scanning of paths.

1. Only include "clojure_test" when test files exist

Before (directory with only core.clj, after #85's docstring + load-before-package):

"""
Do not edit this file manually!
It is automatically generated by the `//:gen_srcs` target from `rules_clojure`.
"""

load("@rules_clojure//:rules.bzl", "clojure_library", "clojure_test")

package(default_visibility = ["//visibility:public"])

clojure_library(name = "core", ...)

After:

"""
Do not edit this file manually!
It is automatically generated by the `//:gen_srcs` target from `rules_clojure`.
"""

load("@rules_clojure//:rules.bzl", "clojure_library")

package(default_visibility = ["//visibility:public"])

clojure_library(name = "core", ...)

2. Skip load() for empty directories

Directories with no source files and no clj subdirs (has-content? false) get a BUILD with only the docstring header + package() — no load, no __clj_lib/__clj_files. Matches Gazelle's behaviour.

Before:

"""
Do not edit this file manually!
It is automatically generated by the `//:gen_srcs` target from `rules_clojure`.
"""

load("@rules_clojure//:rules.bzl", "clojure_library", "clojure_test")

package(default_visibility = ["//visibility:public"])

After:

"""
Do not edit this file manually!
It is automatically generated by the `//:gen_srcs` target from `rules_clojure`.
"""

package(default_visibility = ["//visibility:public"])

Also

• test-path? regex anchored: #"_test.clj" was unanchored — matched _test.cljs, _test.cljbar, etc. Tightened to #"_test\.cljc?$" so the (or clj-path? cljc-path?) guard in has-tests? becomes redundant.
• .clj-kondo/config.edn with exclude-destructured-keys-in-fn-args and exclude-destructured-as — this codebase uses map destructuring in fn args as documentation of expected keys, so unused-binding warnings on those are noise.
• .gitignore adjusted so .clj-kondo/.cache/ is ignored but .clj-kondo/config.edn is tracked.

[english]

Suggested change

	;; ---- gen-dir load-symbol pruning ----
	;; ---- gen-dir load-symbol pruning ----
	;; ---- gen-dir load-symbol pruning ----

[miridius]

Done — duplicated heading removed in c0a9ebf.