M1 security: close the password backdoor, apply re-review, pin E.164

Acts on an adversarial review of the M1 auth and authorization code.
Five findings fixed; the rest recorded in SECURITY-FINDINGS.md as the
M1 exit criteria rather than left in a tool transcript.

- auth: serve /phone-number/request-password-reset, /phone-number/
  reset-password and /sign-in/phone-number as 404. better-auth's
  phoneNumber() registers all three unconditionally -- they are NOT
  gated on emailAndPassword.enabled:false. Left live they form a
  silent second credential path: request-password-reset stores an OTP
  and sends no SMS (sendPasswordResetOTP was never configured, so the
  owner is never told), reset-password mints a bcrypt credential row,
  and sign-in/phone-number then accepts it forever with no OTP. The
  OTP gate still applies, so this is not remote unauthenticated
  takeover -- it converts one momentary OTP compromise into permanent
  access the victim cannot see or rotate.

- auth: drop bearer(). It accepts the plaintext sessions.token column
  as an Authorization credential, making any single leaked row a
  replayable login. The mobile client it was added for is hypothetical.

- auth: pin E.164 via phoneNumberValidator, and add toE164/isE164 to
  @linkder/shared. phone is UNIQUE and bans are per-account, so
  "+34600111222" and "0034600111222" being separately storable meant
  one handset could hold two accounts and a ban was escapable by
  retyping. 15 tests.

- auth: NEXT_PUBLIC_APP_URL now throws in production instead of
  falling back to localhost, which was silently dropping Secure and
  the __Secure- prefix from the production session cookie.

- pro.upsertProfile: actually apply requiresReReview. It was computed,
  returned to the client and never acted on, so a verified plumber
  could become a verified electrician in another city by ignoring a
  response flag. Now demotes to pending in the same transaction and
  audits it. Trade changes count as material (they did not before) --
  the licence is per-trade. Needed a verified -> pending edge in
  VERIFICATION_GRAPH, which did not exist.

Removed two untracked scratch repro files. The impersonation repro
depended on bearer() for transport and no longer applies as written;
the underlying finding (resolveSession drops impersonatedBy, so admin
actions are audited as the victim) is open and documented.

typecheck, lint, build clean; 127 tests pass.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

packages/shared/src/phone.ts

@@ -0,0 +1,55 @@
+/**
+ * Phone identity.
+ *
+ * Phone is the primary identity on this platform, which makes its *string form*
+ * load-bearing: `users.phone` carries a UNIQUE constraint, bans are enforced per
+ * account, and duplicate detection matches on it. If "+34600111222" and
+ * "0034 600 111 222" can both be stored, then one handset holds two distinct
+ * "unique" accounts — which defeats the constraint, lets a banned user return,
+ * and hides the duplicate from `findPossibleDuplicates`.
+ *
+ * So there is exactly one accepted stored form: E.164, no spaces, no separators.
+ * Normalise on the way in, reject anything that cannot be normalised.
+ */
+
+/** E.164: a leading +, a nonzero leading digit, and 8–15 digits total. */
+const E164 = /^\+[1-9]\d{7,14}$/;
+
+export function isE164(value: string): boolean {
+  return E164.test(value);
+}
+
+/**
+ * Coerce common user input into E.164, or return null if it cannot be done
+ * unambiguously.
+ *
+ * Handles the shapes people actually type: spaces, hyphens, parentheses and dots
+ * as separators, and a `00` international prefix instead of `+`. It deliberately
+ * does NOT guess a country code for a bare national number — "600111222" is
+ * meaningless without knowing the country, and silently assuming one would
+ * attach a real person's account to the wrong number.
+ */
+export function toE164(input: string | null | undefined): string | null {
+  if (!input) return null;
+
+  // Strip everything a human might use as a separator.
+  let s = input.trim().replace(/[\s().-]/g, '');
+  if (s.length === 0) return null;
+
+  // "0034..." is the same as "+34..."
+  if (s.startsWith('00')) s = `+${s.slice(2)}`;
+
+  // A bare national number is ambiguous — refuse rather than guess a country.
+  if (!s.startsWith('+')) return null;
+
+  if (!/^\+\d+$/.test(s)) return null;
+  return isE164(s) ? s : null;
+}
+
+/**
+ * Last four digits, for display ("••• ••• 222"). Never render a full number
+ * belonging to someone other than the viewer.
+ */
+export function phoneLast4(e164: string): string {
+  return e164.slice(-4);
+}