feat(marketing): HoM feature-spotlight X drafts + brand-voice charter (v0.18.0 B)

The Head of Marketing now markets features, not just releases: a default-off
x_feature_spotlight loop periodically spawns the HoM to investigate what shipped
(CHANGELOG, feature flags, docs/map, KB) and draft ONE held marketing post via
propose_feature_spotlight, reviewed in the X post queue.

- New x_feature source (distinct from x_post, fixing panel mislabeling) + a
  panel Feature-spotlight branch.
- brand_voice column on company_goals (migration 061, single head) as the
  CEO-editable voice source, surfaced in Settings and injected into the HoM
  briefing; a VOICE GUIDE baseline in head-marketing.md.
- propose_feature_spotlight verb (HoM-only), mirroring propose_roadmap.

Gated by x_feature_spotlight_enabled (default off; flag-off dormancy proven).
Also fixed two real bugs found mid-build: company_goals API schemas dropped
brand_voice on GET/PUT; the live charter UI is goals-tab.tsx, not the unmounted
company-goals-card.tsx. Full suite green (2935); migration single-head verified.

alembic/versions/061_x_feature_spotlight.py

@@ -0,0 +1,45 @@
+"""Add x_seen_features table + company_goals.brand_voice — feature-spotlight.
+
+``x_seen_features`` is the feature-spotlight dedup ledger, keyed by feature
+slug so a shipped capability is never spotlighted twice (mirrors
+``x_seen_mentions``). ``company_goals.brand_voice`` is the CEO-authored
+brand-voice sample/direction, a dedicated Text column mirroring
+``north_star`` (not folded into the catch-all ``operating_policy`` JSON
+blob). Additive and inert while ``ROBOCO_X_FEATURE_SPOTLIGHT_ENABLED`` is off.
+
+Revision ID: 061_x_feature_spotlight
+Revises: 060_drop_messaging
+Create Date: 2026-07-04
+"""
+
+from __future__ import annotations
+
+import sqlalchemy as sa
+from alembic import op
+
+revision = "061_x_feature_spotlight"
+down_revision = "060_drop_messaging"
+branch_labels: dict[str, str] | None = None
+depends_on: dict[str, str] | None = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "x_seen_features",
+        sa.Column("feature_slug", sa.String(length=128), primary_key=True),
+        sa.Column(
+            "seen_at",
+            sa.DateTime(timezone=True),
+            nullable=False,
+            server_default=sa.text("now()"),
+        ),
+    )
+    op.add_column(
+        "company_goals",
+        sa.Column("brand_voice", sa.Text(), nullable=False, server_default=""),
+    )
+
+
+def downgrade() -> None:
+    op.drop_column("company_goals", "brand_voice")
+    op.drop_table("x_seen_features")