chore(comments): drop epic, sprint and review-round ids from the code

The code cited its plan instead of saying why: `E28 review J4`, `(R6 S3b)`, `S1 justified…`,
`deep-review round 5`. That plan lives in the private ops repo, so for every reader of this one the
citation was noise, and a sentence whose subject was the plan step ("round 2 showed…") hid its
lesson behind an id. Each one is gone and the "why" kept: a bare citation is deleted, a sentence
carrying a lesson is reworded around it ("a later attempt showed…").

Measured (`scripts/audit_metrics.py`, product code): 652 lines in 270 files carried an epic code by
the definition the next commit holds (507 / 241 by the old, two-digit-only one) -> 0. Across all
code, tests, scripts and configs: ~1100 epic-code lines plus ~320 sprint/round ids.

Behaviour unchanged, checked mechanically: every changed .py file has the same AST once docstrings
are blanked; css/sh/toml/yml/json files are identical once comments are stripped; the only
non-comment changes in TS/JS are test titles, one description string in a contract table, and five
ESLint messages, whose text is all the gates snapshot diff holds. Not touched: Markdown (docs and
the changelog keep their history), Alembic migrations, TV episode notation (`S2 · E5`), DESIGN.md
ids (`C1`, `B4`, `S3h`), tracker ids (`SEC-16`, `DX-17`).

One stale claim fixed on the way: test_hls_reaper's docstring said the player checkpoints "every
10 s whether or not it is playing", which plex/stream.py calls wrong; it now says what the code does.

frontend/e2e/channel.spec.ts

@@ -30,7 +30,7 @@ test.describe("channel view", () => {
     await expect(page.getByTestId("video-card").first()).toBeVisible();
   });
 
-  // Bug 1 (Platform S4): opening a channel and coming Back restores the feed's scroll position
+  // Opening a channel and coming Back restores the feed's scroll position
   // rather than dumping you at the top. The shell owns the scroller and remembers each view's offset.
   test("Back restores the feed scroll position", async ({ page }) => {
     await openApp(page);
@@ -60,7 +60,7 @@ test.describe("channel view", () => {
       .toBeGreaterThan(saved - 500);
   });
 
-  // Bug 2 (Platform S5): opening a channel no longer FORCES Live/Upcoming on — the channel view
+  // Opening a channel no longer FORCES Live/Upcoming on — the channel view
   // seeds its content-type prefs (normal / shorts / live) from the global feed. Locked both ways so
   // a future refactor can't silently re-hardcode it.
   test("the channel view inherits the feed's content filters (no forced Live/Upcoming)", async ({
@@ -86,7 +86,7 @@ test.describe("channel view", () => {
     await expectContentType(page, "includeLive", true);
   });
 
-  // Bug 2 (Platform S5): the channel view is its OWN filter scope — a content toggle made there
+  // The channel view is its OWN filter scope — a content toggle made there
   // must NOT leak back into the global feed. (FeedFiltersProvider owns the feed's filters; the
   // channel page keeps a separate local cell.)
   test("a channel's content toggle does not leak into the feed", async ({ page }) => {
@@ -106,7 +106,7 @@ test.describe("channel view", () => {
     await expectContentType(page, "includeLive", false);
   });
 
-  // Platform S4b + E31 S4c: the channel chrome sits outside the scroller. Scrolling into the videos
+  // The channel chrome sits outside the scroller. Scrolling into the videos
   // folds the banner and identity once (the name moves into the tab row); from then on the folded
   // chrome stays put while only the video grid scrolls.
   test("the channel chrome folds once, then stays fixed while the grid scrolls", async ({

frontend/e2e/feed.spec.ts

@@ -51,7 +51,7 @@ test.describe("feed", () => {
       .toBe(true);
   });
 
-  // Bug 4 (Platform S4): the toolbar (show/content chips, count, sort, view) is fixed chrome — it
+  // The toolbar (show/content chips, count, sort, view) is fixed chrome — it
   // pins in the shell's toolbar band above the scroller, so it stays put while the cards scroll.
   test("the feed toolbar stays pinned while cards scroll", async ({ page }) => {
     await openApp(page);
@@ -66,7 +66,7 @@ test.describe("feed", () => {
     expect(Math.abs(topAfter - topBefore)).toBeLessThan(4);
   });
 
-  // Bug 3 (Platform S4): changing a filter is a fresh result set, so the scroll jumps back to the
+  // Changing a filter is a fresh result set, so the scroll jumps back to the
   // top rather than stranding you deep in the old list's offset.
   test("a new filter resets the scroll to the top", async ({ page }) => {
     await openApp(page);

frontend/e2e/global.setup.ts

@@ -76,7 +76,7 @@ setup("seed + authenticate", async ({ page }) => {
 
   // 4. Pin the UI locale, suppress the first-login onboarding wizard (a full-screen overlay
   //    that would intercept every click — the test account has no YouTube connection, so it
-  //    auto-opens), and opt the account out of starting on Home. Since E24 a bare URL lands on
+  //    auto-opens), and opt the account out of starting on Home. A bare URL lands on
   //    Home, and the feed, channel and player flows this net locks all open "/" expecting the
   //    feed; the opt-out is the one Settings → Appearance → Startup writes. Both flags are
   //    per-account: `siftlode.onboarding.dismissed.<id>`, `siftlode.startOnHome.<id>`.

frontend/e2e/helpers.ts

@@ -18,7 +18,7 @@ export async function gotoPage(page: Page, id: string): Promise<void> {
  * Playwright would scroll it into view to click it, moving the scroll position — fatal to any test
  * that then asserts on where the feed was. Being inside the viewport is not enough either: a card
  * can sit under the page chrome above the scroller (the update banner, the toolbar band), and the
- * covered click makes Playwright scroll and retry — the same move (E32 S2: webkit failed 3 in 24).
+ * covered click makes Playwright scroll and retry — the same move (webkit failed 3 in 24).
  * So the link must be the element hit at its own centre. Returns false if none found.
  */
 export async function clickVisibleChannelLink(page: Page): Promise<boolean> {

frontend/e2e/nav.spec.ts

@@ -6,9 +6,9 @@ import { openApp } from "./helpers";
 // this exercises is precisely what the module-registry refactor replaces.
 test.describe("page switching", () => {
   // Core + admin modules (the E2E account is an admin, matching the real primary user), so this
-  // also exercises the admin pages. Since E31 those sit behind ONE rail row ("Administration",
+  // also exercises the admin pages. They sit behind ONE rail row ("Administration",
   // `nav-admin`) that opens a panel of them — the spec still listed them as rail rows of their own,
-  // and it failed on every run from E31 to E32 without anyone seeing it, because e2e was in no
+  // and it failed on every run for a while without anyone seeing it, because e2e was in no
   // required gate (it is now part of `release`).
   const RAIL = ["channels", "playlists", "stats", "settings", "feed"];
   const ADMIN = ["scheduler", "config", "users", "audit"];

frontend/e2e/player.spec.ts

@@ -2,7 +2,7 @@ import { test, expect } from "@playwright/test";
 import { openApp, openFirstVideo } from "./helpers";
 
 // Locks the in-app player's open/close contract. The player is a portaled overlay whose
-// inconsistent mounting caused an E3 regression — exactly the kind of thing the refactor's
+// inconsistent mounting caused a regression — exactly the kind of thing the refactor's
 // overlay-root convention must not break. We assert the modal shell, not YouTube playback.
 test.describe("player modal", () => {
   test.beforeEach(async ({ page }) => {

frontend/e2e/tsconfig.json

@@ -11,7 +11,7 @@
     "noUnusedLocals": true,
     "noUnusedParameters": true,
     "noFallthroughCasesInSwitch": true,
-    // E32: an index read is `T | undefined` here, as it really is (0 errors when switched on).
+    // An index read is `T | undefined` here, as it really is (0 errors when switched on).
     "noUncheckedIndexedAccess": true,
     "esModuleInterop": true,
     "resolveJsonModule": true