finish phase 4: drop @atproto/api dependency, lex-only errors, delete toLex and legacy validators

oxlint-suppressions.json gains a baseline entry for webpack.config.js: the
file was never previously staged/linted (lint script covers src+modules
only), and editing it exposed its pre-existing violations to lint-staged.
All suppressed counts are pre-existing; this change only removes a line.

src/state/messages/convo/agent.ts

@@ -66,8 +66,8 @@ function toSystemMessageView(
    * The guard disjunction is kept inline in the `if` (rather than a separate
    * boolean) so TS narrows `ev` to the union of system-message log types, all
    * of which carry a `message: SystemMessageView`. The generated lexicon types
-   * are stricter than the old `@atproto/api` ones (no `[k: string]: unknown`
-   * index signature), so a separate boolean would not narrow the access.
+   * are strict (no `[k: string]: unknown` index signature), so a separate
+   * boolean would not narrow the access.
    */
   if (
     bsky.isType(chat.bsky.convo.defs.logAddMember, ev) ||

src/state/queries/explore-feed-previews.tsx

@@ -205,7 +205,7 @@ export function useFeedPreviews(
               if (item.isFallbackMarker) continue
 
               const moderations = item.items.map(item =>
-                // @atproto/api and yields lex-typed slice items.
+                // the tuner yields lex-typed slice items.
                 moderatePost(item.post, moderationOpts!),
               )
 
@@ -232,7 +232,7 @@ export function useFeedPreviews(
                     const feedPostSliceItem: FeedPostSliceItem = {
                       _reactKey: `${item._reactKey}-${i}-${subItem.post.uri}`,
                       uri: subItem.post.uri,
-                      // off @atproto/api and yields lex-typed slice items.
+                      // the tuner yields lex-typed slice items.
                       post: subItem.post,
                       record: subItem.record,
                       moderation: moderations[i],

src/state/queries/post-feed.ts

@@ -288,7 +288,7 @@ export function usePostFeedQuery(
                 .map(slice => {
                   const moderations = slice.items.map(item =>
                     moderatePost(
-                      // off @atproto/api and yields lex-typed slice items.
+                      // the tuner yields lex-typed slice items.
                       item.post,
                       moderationOpts!,
                     ),
@@ -341,7 +341,7 @@ export function usePostFeedQuery(
                       const feedPostSliceItem: FeedPostSliceItem = {
                         _reactKey: `${slice._reactKey}-${i}-${item.post.uri}`,
                         uri: item.post.uri,
-                        // off @atproto/api and yields lex-typed slice items.
+                        // the tuner yields lex-typed slice items.
                         post: item.post,
                         record: item.record,
                         moderation: moderations[i],

src/state/queries/search-posts-params.ts

@@ -289,8 +289,8 @@ export function buildSearchPostsV2Filters(
 }
 
 /**
- * Consistent with timestamp parsing in @atproto/api. Only the date is used; the
- * time is appended here since the lexicon expects a datetime value.
+ * Consistent with atproto timestamp parsing. Only the date is used; the time
+ * is appended here since the lexicon expects a datetime value.
  */
 const parseTimestamp = (value: string | undefined): string | undefined => {
   if (!value) return undefined