feat: add is_bot_message column and support dedicated phone numbers (#235)

* feat: add is_bot_message column and support dedicated phone numbers

Replace fragile content-prefix bot detection with an explicit
is_bot_message database column. The old prefix check (content NOT LIKE
'Andy:%') is kept as a backstop for pre-migration messages.

- Add is_bot_message column with automatic backfill migration
- Add ASSISTANT_HAS_OWN_NUMBER env var to skip name prefix when the
  assistant has its own WhatsApp number
- Move prefix logic into WhatsApp channel (no longer a router concern)
- Remove prefixAssistantName from Channel interface
- Load .env via dotenv so launchd-managed processes pick up config
- WhatsApp bot detection: fromMe for own number, prefix match for shared

Based on #160 and #173.

Co-Authored-By: Stefan Gasser <stefan@stefangasser.com>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* refactor: extract shared .env parser and remove dotenv dependency

Extract .env parsing into src/env.ts, used by both config.ts and
container-runner.ts. Reads only requested keys without loading secrets
into process.env, avoiding leaking API keys to child processes.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Stefan Gasser <stefan@stefangasser.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

src/formatting.test.ts

@@ -1,13 +1,13 @@
 import { describe, it, expect } from 'vitest';
 
-import { ASSISTANT_NAME, TRIGGER_PATTERN } from './config.js';
+import { TRIGGER_PATTERN } from './config.js';
 import {
   escapeXml,
   formatMessages,
   formatOutbound,
   stripInternalTags,
 } from './router.js';
-import { Channel, NewMessage } from './types.js';
+import { NewMessage } from './types.js';
 
 function makeMsg(overrides: Partial<NewMessage> = {}): NewMessage {
   return {
@@ -162,34 +162,18 @@ describe('stripInternalTags', () => {
 });
 
 describe('formatOutbound', () => {
-  const waChannel = { prefixAssistantName: true } as Channel;
-  const noPrefixChannel = { prefixAssistantName: false } as Channel;
-  const defaultChannel = {} as Channel;
-
-  it('prefixes with assistant name when channel wants it', () => {
-    expect(formatOutbound(waChannel, 'hello world')).toBe(
-      `${ASSISTANT_NAME}: hello world`,
-    );
-  });
-
-  it('does not prefix when channel opts out', () => {
-    expect(formatOutbound(noPrefixChannel, 'hello world')).toBe('hello world');
-  });
-
-  it('defaults to prefixing when prefixAssistantName is undefined', () => {
-    expect(formatOutbound(defaultChannel, 'hello world')).toBe(
-      `${ASSISTANT_NAME}: hello world`,
-    );
+  it('returns text with internal tags stripped', () => {
+    expect(formatOutbound('hello world')).toBe('hello world');
   });
 
   it('returns empty string when all text is internal', () => {
-    expect(formatOutbound(waChannel, '<internal>hidden</internal>')).toBe('');
+    expect(formatOutbound('<internal>hidden</internal>')).toBe('');
   });
 
-  it('strips internal tags and prefixes remaining text', () => {
+  it('strips internal tags from remaining text', () => {
     expect(
-      formatOutbound(waChannel, '<internal>thinking</internal>The answer is 42'),
-    ).toBe(`${ASSISTANT_NAME}: The answer is 42`);
+      formatOutbound('<internal>thinking</internal>The answer is 42'),
+    ).toBe('The answer is 42');
   });
 });