fix(cli): make skills update converge on a skill retired upstream (#2176)

`hyperframes skills update` failed hard or looped forever once a skill was
retired/renamed upstream while still installed locally (hyperframes-media folded
into media-use; hyperframes-captions/compose/tts consolidated earlier). Two
paths dead-ended:

- Install: target selection could trust a stale local skills-manifest.json
  (findRepoManifest) while `skills add` always installs from the canonical repo.
  isCoreSkill matches the `hyperframes-` prefix, so a retired skill was forced
  into the target set, `skills add` silently declined it (exit 0), and strict
  verifyInstalled threw "Skill(s) still missing after install".
- Prune: upstream `skills remove` scans on-disk directories, so a lock entry
  retired before it ever shipped a bundle has nothing to match — a silent
  exit-0 no-op that never clears the lock, so detectRemoved re-flags it on
  every run.

The stale-skills nudge compounded it: it fired even from `skills update` itself
(pointing users back at the failing command) and its count ignored the removed
bucket.

Resolve update targets against the canonical manifest (checkSkills({ canonical:
true })) so a retired skill is never targeted. Add pruneOrphanedLockEntries to
clear the orphaned lock entries the upstream remover can't (idempotent, so a
second run is a clean no-op). Exclude `skills` from the update-nudge gate and
thread the removed count through the nudge total.

packages/cli/src/telemetry/config.ts

@@ -63,6 +63,8 @@ export interface HyperframesConfig {
   skillsOutdatedCount?: number;
   /** How many skills were missing (not installed) at the last check. */
   skillsMissingCount?: number;
+  /** How many installed skills were flagged removed-upstream at the last check. */
+  skillsRemovedCount?: number;
 }
 
 const DEFAULT_CONFIG: HyperframesConfig = {
@@ -108,6 +110,7 @@ export function readConfig(): HyperframesConfig {
       skillsUpdateAvailable: parsed.skillsUpdateAvailable,
       skillsOutdatedCount: parsed.skillsOutdatedCount,
       skillsMissingCount: parsed.skillsMissingCount,
+      skillsRemovedCount: parsed.skillsRemovedCount,
     };
 
     cachedConfig = config;