bring repo into policy compliance; vendor assets; Gitea CI

Vendor the front-end assets and drop the third-party CDN dependencies
(BootstrapCDN is being sunset): the bootstrap 4.0.0 css/js, jquery
3.2.1 slim, and popper 1.12.9 now live under static/ and are served
from the app, byte-for-byte identical to the previous SRI-pinned files.

Migrate CI from Drone to a Gitea Actions workflow that runs
docker build . on push, with the checkout action pinned by SHA.

Bring the repo up to standard:

- add REPO_POLICIES.md, .editorconfig, .dockerignore, .golangci.yml,
  and a comprehensive root-anchored .gitignore
- rewrite the Makefile with the required test/lint/fmt/fmt-check/check/
  docker/hooks targets (golangci-lint, 30s test timeout, verbose rerun
  on failure, check modifies nothing)
- rewrite the Dockerfile as a hash-pinned multistage build: a lint
  stage (golangci-lint), a glibc build+test stage (the legacy sqlite
  driver needs cgo+glibc), and a debian-slim runtime carrying the
  binary, templates, and static assets
- add real tests for the hn package
- bring the code into golangci-lint (default: all) compliance: fix the
  malformed gorm struct tags, check previously-ignored errors, dispatch
  the zerolog error event, avoid a uint->Duration overflow, split long
  functions, and add doc comments — all behaviour-preserving
- expand the README with the required sections

hn/handlers.go

@@ -10,38 +10,58 @@ import (
 	"github.com/labstack/echo"
 )
 
+// RequestHandlerSet holds the dependencies shared by the HTTP handlers.
 type RequestHandlerSet struct {
 	db      *gorm.DB
 	version string
 }
 
+// NewRequestHandlerSet builds a RequestHandlerSet for the given version and
+// database handle.
 func NewRequestHandlerSet(version string, db *gorm.DB) *RequestHandlerSet {
 	rhs := new(RequestHandlerSet)
 	rhs.db = db
 	rhs.version = version
+
 	return rhs
 }
 
-func (r *RequestHandlerSet) indexHandler(c echo.Context) error {
+// exitRow is a story that has left the front page within the last 24h.
+type exitRow struct {
+	Duration     string
+	DurationSecs uint
+	URL          string
+	Title        string
+	HighestRank  uint
+	HNID         uint
+	Score        uint
+	TimeGone     string
+	TimeGoneSecs uint
+}
+
+// currentRow is a story currently on the front page.
+type currentRow struct {
+	Duration     string
+	DurationSecs uint
+	URL          string
+	Title        string
+	Score        uint
+	HighestRank  uint
+	HNID         uint
+	Rank         uint
+}
+
+// exitedRows returns the stories that left the front page in the last 24h,
+// most recently departed first.
+func (r *RequestHandlerSet) exitedRows() []exitRow {
 	last24h := time.Now().Add(time.Second * 86400 * -1)
+
 	var fpi []HNFrontPage
 	r.db.Where("disappeared is not ? and disappeared > ?", time.Time{}, last24h).Order("disappeared desc").Find(&fpi)
 
-	type fprow struct {
-		Duration     string
-		DurationSecs uint
-		URL          string
-		Title        string
-		HighestRank  uint
-		HNID         uint
-		Score        uint
-		TimeGone     string
-		TimeGoneSecs uint
-	}
-	var fprows []fprow
-
+	rows := make([]exitRow, 0, len(fpi))
 	for _, item := range fpi {
-		fprows = append(fprows, fprow{
+		rows = append(rows, exitRow{
 			Duration:     u.TimeDiffHuman(item.Disappeared, item.Appeared),
 			DurationSecs: u.TimeDiffAbsSeconds(item.Disappeared, item.Appeared),
 			URL:          item.URL,
@@ -54,23 +74,17 @@ func (r *RequestHandlerSet) indexHandler(c echo.Context) error {
 		})
 	}
 
-	type rowtwo struct {
-		Duration     string
-		DurationSecs uint
-		URL          string
-		Title        string
-		Score        uint
-		HighestRank  uint
-		HNID         uint
-		Rank         uint
-	}
-	var currentfp []rowtwo
+	return rows
+}
 
+// currentRows returns the stories currently on the front page, best rank first.
+func (r *RequestHandlerSet) currentRows() []currentRow {
 	var cur []HNFrontPage
 	r.db.Where("disappeared is ?", time.Time{}).Order("rank asc").Find(&cur)
 
+	rows := make([]currentRow, 0, len(cur))
 	for _, item := range cur {
-		currentfp = append(currentfp, rowtwo{
+		rows = append(rows, currentRow{
 			Duration:     u.TimeDiffHuman(time.Now(), item.Appeared),
 			DurationSecs: u.TimeDiffAbsSeconds(time.Now(), item.Appeared),
 			URL:          item.URL,
@@ -82,12 +96,17 @@ func (r *RequestHandlerSet) indexHandler(c echo.Context) error {
 		})
 	}
 
+	return rows
+}
+
+func (r *RequestHandlerSet) indexHandler(c echo.Context) error {
 	tc := pongo2.Context{
 		"time":    time.Now().UTC().Format(time.RFC3339Nano),
-		"exits":   fprows,
-		"current": currentfp,
+		"exits":   r.exitedRows(),
+		"current": r.currentRows(),
 		"gitrev":  r.version,
 	}
+
 	return c.Render(http.StatusOK, "index.html", tc)
 }
 
@@ -96,5 +115,6 @@ func (r *RequestHandlerSet) aboutHandler(c echo.Context) error {
 		"time":   time.Now().UTC().Format(time.RFC3339Nano),
 		"gitrev": r.version,
 	}
+
 	return c.Render(http.StatusOK, "about.html", tc)
 }