v0.3 step 1: migration 0004 + authors module + web form panels

Migration 0004 — authors + author_revisions + stories.author_id +
stories.author_revision_id + stories.cross_story_memory +
author_corpus. Soul versioning built in from day one per Sulkta's
locked decisions:
- authors.id immutable identity (slug + display_name + tagline + model)
- author_revisions tracks each soul revision with n monotonic
- Partial unique index 'idx_author_revisions_current' enforces
  exactly one is_current=true per author
- stories.author_revision_id pins to the exact soul used at gen
  time (so 'this was the Orson Black active when chapter 8 was
  written' is always recoverable)
- author_corpus tracks 'authored' + 'read' relationships for the
  v0.3 cross-story memory toggle

skald-core::authors module — CRUD: get_by_slug,
get_with_current_revision, get_current_revision, get_revision,
create_or_get (idempotent), add_revision (transactional, demotes
prior is_current=true), assign_to_story (also touches
author_corpus).

Web v0.1 forms (the second feedback bucket — 'no way to make new
stories', 'no options for sequels'): handlers + form panels +
POST routes for /stories/new and /stories/:id/continue. Both
create a story stub with status='seed'; actual generation will be
fired by 'skald continue' (next commit) walking seed rows.

Norse visual revamp + mobile collapse deferred — vetting full gen
is the priority per Sulkta's 'green light for v0.3'. Coming back to
the aesthetic after the pipeline works end-to-end against a real
Orson Black-authored Chapter 8 of Coast-Down.

migrations/0004_authors.sql

@@ -0,0 +1,100 @@
+-- Authors as personas with souls (v0.3).
+--
+-- Each story has a named author whose soul (persona-soul-style markdown
+-- blob) IS the LLM's system prompt. Soul replaces opus's default
+-- base prompt via clawdforge's system_mode='replace' so the model
+-- BECOMES the author, not "Claude playing the author."
+--
+-- Souls are versioned: authors.id is the immutable identity, while
+-- author_revisions tracks soul edits over time. Stories pin to a
+-- specific revision so "this was the version of Orson Black active
+-- when chapter 8 of Coast-Down was written" is always recoverable.
+
+CREATE TABLE authors (
+    id              UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    slug            TEXT NOT NULL UNIQUE,           -- "orson-black"
+    display_name    TEXT NOT NULL,                  -- "Orson Black"
+    persona_tagline TEXT,                           -- "Orwell but more rebel + pissed off"
+    -- Model the author writes with. Skald is opinionated: always
+    -- opus max effort. Stored per-author so we can later vary
+    -- (e.g. test sonnet for a faster-iterating author).
+    model           TEXT NOT NULL DEFAULT 'opus',
+    -- Flag for the operator: this is a synthetic literary persona,
+    -- not a real human author. Display somewhere obvious.
+    is_synthetic    BOOLEAN NOT NULL DEFAULT true,
+    created_at      TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at      TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+-- One row per soul revision. `n` is monotonic per author. Exactly
+-- one revision per author is_current=true at any time (partial
+-- unique index).
+CREATE TABLE author_revisions (
+    id              UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    author_id       UUID NOT NULL REFERENCES authors(id) ON DELETE CASCADE,
+    n               INTEGER NOT NULL,
+    -- The soul: persona-soul-style markdown blob. Replaces claude's base
+    -- system prompt when this revision is used.
+    soul            TEXT NOT NULL,
+    -- Optional override of the default scaffold prompt that wraps
+    -- the soul. Default scaffold lives in skald-core::forge.
+    system_template TEXT,
+    -- Tools the author can call during gen. Empty default — fiction
+    -- writing doesn't normally need them. Researcher-bent authors
+    -- could opt in for WebSearch / Read.
+    tools           TEXT[] NOT NULL DEFAULT '{}',
+    -- Human note: "first cut", "tightened voice after Chapter 8 read"
+    note            TEXT,
+    is_current      BOOLEAN NOT NULL DEFAULT false,
+    created_at      TIMESTAMPTZ NOT NULL DEFAULT now(),
+    UNIQUE (author_id, n)
+);
+
+-- At most one current revision per author.
+CREATE UNIQUE INDEX idx_author_revisions_current
+    ON author_revisions(author_id) WHERE is_current = true;
+
+CREATE INDEX idx_author_revisions_author ON author_revisions(author_id);
+
+-- Auto-touch authors.updated_at on author or revision change.
+CREATE OR REPLACE FUNCTION touch_author_updated_at()
+RETURNS TRIGGER AS $$
+BEGIN
+    UPDATE authors SET updated_at = now()
+    WHERE id = COALESCE(NEW.author_id, OLD.author_id);
+    RETURN COALESCE(NEW, OLD);
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE TRIGGER author_revisions_touch_author
+    AFTER INSERT OR UPDATE OR DELETE ON author_revisions
+    FOR EACH ROW
+    EXECUTE FUNCTION touch_author_updated_at();
+
+-- Stories carry author identity + the exact revision used at gen
+-- time. author_id is also denormalized on the row (instead of
+-- joining through revision) so common "all stories by Orson"
+-- queries don't need the join.
+ALTER TABLE stories
+    ADD COLUMN author_id           UUID REFERENCES authors(id) ON DELETE SET NULL,
+    ADD COLUMN author_revision_id  UUID REFERENCES author_revisions(id) ON DELETE SET NULL,
+    -- Per-story toggle for cross-story memory. When true,
+    -- ContinuationContext::assemble pulls characters / canon /
+    -- summaries from EVERY story in the author's corpus, not just
+    -- the parent chain.
+    ADD COLUMN cross_story_memory  BOOLEAN NOT NULL DEFAULT false;
+
+CREATE INDEX idx_stories_author ON stories(author_id);
+
+-- Track which stories an author has access to. Auto-populated via
+-- app code on every story creation (role='authored'); operator can
+-- mark other stories as 'read' for cross-corpus memory.
+CREATE TABLE author_corpus (
+    author_id   UUID NOT NULL REFERENCES authors(id) ON DELETE CASCADE,
+    story_id    UUID NOT NULL REFERENCES stories(id) ON DELETE CASCADE,
+    role        TEXT NOT NULL CHECK (role IN ('authored', 'read')),
+    added_at    TIMESTAMPTZ NOT NULL DEFAULT now(),
+    PRIMARY KEY (author_id, story_id)
+);
+
+CREATE INDEX idx_author_corpus_author ON author_corpus(author_id);