Align codebase with the V1 production brief

Reconciles the implementation against the final MVP brief:

- Data model: rename users.provider to auth_provider and
  users.subscription_status to subscription, matching the brief's schema
  exactly (id, email, auth_provider, subscription, created_at). External
  API field names are unchanged.
- Suggestions: replace the starter list with the brief's eight examples.
- Instructions: personality updated to calm, warm, intelligent, curious,
  respectful, pedagogical — never judging, manipulative, dramatic,
  overly positive, overconfident or preaching. Added per-reply goals:
  feel personal, be calm, instill safety, give hope without promising
  results, deepen thinking, and always contain at least one genuinely
  new thought or question. Added the conversation outcome goal (greater
  clarity, greater calm, a new perspective, increased trust in one's own
  ability) and 'not a chatbot for general questions' to positioning.
- Paywall transition example updated to the brief's wording ('I'm
  starting to see some recurring patterns… Unlock Premium to continue.').
- Knowledge base completed per the brief: communication models
  (perceptual positions, observation vs interpretation, chunking,
  backtracking, boundaries), reflection exercises (meaning audit,
  meta-question, five frames, observer replay, well-formed outcome,
  evening question) and a question library organized by purpose.
  Appreciation in the Lift step must be anchored in what the user
  actually expressed; the Challenge step never preaches.
- README: product principle (one user, one conversation, one analysis,
  one recommendation), the removal rule, design words per the brief,
  Definition of Done (7 steps), V2 not-now list (journal, saved
  insights, community, coaches, courses, voice), and a closed-beta plan
  for 20-50 testers with what the minimal data model can already
  measure.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0118DaxZR36RpnY524vRqx3z

db/migrations/001_init.sql

@@ -2,10 +2,10 @@
 -- no conversations, no profiling data.
 
 create table if not exists users (
-  id text primary key, -- Cognito sub
+  id text primary key, -- Cognito sub, or guest:<device-id>
   email text not null,
-  provider text not null, -- 'apple' | 'google' | 'email'
-  subscription_status text not null default 'free', -- 'free' | 'active'
+  auth_provider text not null, -- 'apple' | 'google' | 'email' | 'guest'
+  subscription text not null default 'free', -- 'free' | 'active'
   created_at timestamptz not null default now()
 );