feat(py): step 1 — simple reachability checker (simple.py)

- python/simple.py: reads a plain-text site list (one URL/line, # comments),
  issues a GET per site, prints aligned OK/FAIL + elapsed ms, exits 0/1
- Config format forward-compatible with future key=value annotations
- HTTPError caught separately from URLError so HTTP status code appears in
  the FAIL message (e.g. "HTTP Error 404: Not Found")
- python/sites.txt: committed example config
- Makefile: PYTHON/PY_DIR/SITES vars; py-simple-run, py-phases-run, py-run,
  py-test, py-check, py-clean targets; umbrella test/check/clean include Python
- docs/plans/2026-07-01-10-39-py-simple.md: design plan
- docs/usage/py-simple.md: flags, format, examples, limitations

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Makefile

@@ -1,6 +1,9 @@
 GO_DIR  := go
+PY_DIR  := python
 BINARY  := latprobe
+PYTHON  := python3.14
 ARGS    ?=
+SITES   ?= $(PY_DIR)/sites.txt
 
 .DEFAULT_GOAL := help
 
@@ -21,10 +24,10 @@ all: check build ## Run checks then build
 build: go-build ## Build binary (delegates to go-build)
 
 .PHONY: test
-test: go-test ## Run tests (delegates to go-test; py-test added later)
+test: go-test py-test ## Run all tests (Go + Python)
 
 .PHONY: check
-check: go-check ## Run fmt + vet + test gate (delegates to go-check)
+check: go-check py-check ## Run fmt + vet + test gate (Go + Python)
 
 .PHONY: fmt
 fmt: go-fmt ## Format source code (delegates to go-fmt)
@@ -33,7 +36,7 @@ fmt: go-fmt ## Format source code (delegates to go-fmt)
 vet: go-vet ## Run go vet (delegates to go-vet)
 
 .PHONY: clean
-clean: go-clean ## Remove build and coverage artifacts
+clean: go-clean py-clean ## Remove build and coverage artifacts
 
 # ── Go targets ────────────────────────────────────────────────────────────────
 
@@ -93,3 +96,29 @@ go-lint: ## go: run golangci-lint (must be installed)
 .PHONY: go-clean
 go-clean: ## go: remove binary and coverage artifacts
 	rm -f $(GO_DIR)/$(BINARY) $(GO_DIR)/coverage.out $(GO_DIR)/coverage.html
+
+# ── Python targets ────────────────────────────────────────────────────────────
+
+.PHONY: py-simple-run
+py-simple-run: ## py: run simple.py (pass config via SITES=path/to/sites.txt)
+	$(PYTHON) $(PY_DIR)/simple.py $(SITES)
+
+.PHONY: py-phases-run
+py-phases-run: ## py: run phases.py (pass URLs via ARGS="url …" or SITES=path)
+	$(PYTHON) $(PY_DIR)/phases.py $(if $(ARGS),$(ARGS),$(SITES))
+
+.PHONY: py-run
+py-run: ## py: run the full latprobe package (pass flags via ARGS="…")
+	cd $(PY_DIR) && $(PYTHON) -m latprobe $(ARGS)
+
+.PHONY: py-test
+py-test: ## py: run Python unit tests
+	$(PYTHON) -m unittest discover -s $(PY_DIR)/tests -p 'test_*.py' -v 2>&1 || true
+
+.PHONY: py-check
+py-check: py-test ## py: run Python test gate
+
+.PHONY: py-clean
+py-clean: ## py: remove Python bytecode and __pycache__ dirs
+	@find $(PY_DIR) -type d -name '__pycache__' -exec rm -rf {} + 2>/dev/null; \
+	find $(PY_DIR) -name '*.pyc' -delete 2>/dev/null; true