docs: plan-era "v1", "Task N" and "Phase N" wording restated as facts (#6277)

The marker list behind the earlier server and web passes did not catch
"for v1", "Task 5", "Phase 2" or "today: Flutter". Those comments now say
what the code does.

Corrected: coverart said "both v1 providers" ship on. There are four
providers (MBCAA, TheAudioDB, Deezer, Last.fm), and Last.fm, which needs a
key, ships off.

Non-comment tokens unchanged against HEAD: 10 Go files, 7 TS/Svelte files.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/recommendation/candidates.go

@@ -92,7 +92,7 @@ type CandidateSourceLimits struct {
 	UserCoplay int
 }
 
-// DefaultCandidateSourceLimits returns the v1 hardcoded constants per spec.
+// DefaultCandidateSourceLimits returns the hardcoded per-source limits.
 func DefaultCandidateSourceLimits() CandidateSourceLimits {
 	return CandidateSourceLimits{
 		LBSimilar:     30,

internal/recommendation/similarity.go

@@ -1,8 +1,7 @@
 package recommendation
 
 // SimilarityWeights balances the per-axis contribution to the weighted Jaccard
-// score. v1 hardcodes the defaults — operators cannot tune via YAML. If
-// telemetry justifies it, expose under recommendation.similarity.* later.
+// score. The defaults are hardcoded; there is no config key for them.
 type SimilarityWeights struct {
 	TagsWeight    float64
 	ArtistsWeight float64