fix: remove duplicate packages/bot, fix remaining build breaks

[CSTRSK]

Fixes #943

packages/bot/* is an abandoned, unpublished duplicate of packages/bots/* with zero external consumers (the only references are the five packages pointing at each other). It is still compiled by pnpm -r build, so defects there break the workspace build for everyone — exactly what happened in #942.

Changes

1. Delete packages/bot/* entirely (core/discord/signal/telegram/whatsapp — the dead tree). No code references it: no package.json depends on @sh1pt/bot-*, no tsconfig/CI references packages/bot.
2. packages/bots/core: annotate finish() with AIResult instead of a widened inline type — fixes TS2345: type 'string' not assignable to type '"result"'.
3. packages/bots/signal: fix outdated test object — groupId: undefined → null, drop non-existent raw field, add required isGroup.

Verification

• pnpm -r build: all packages Done, zero failures (was: bot/core + bots/core + bots/signal failing)
• tsc -p tsconfig.json --noEmit clean in bots/core and bots/signal

[github-actions]

🤖 Auto-rebase failed: This branch has conflicts with master that cannot be resolved automatically. Conflicting files: packages/bot/core/src/index.ts. Please rebase manually: git fetch upstream master && git rebase upstream/master.

[github-actions]

🤖 Auto-rebase failed: This branch has conflicts with master that cannot be resolved automatically. Conflicting files: packages/bot/core/src/index.ts. Please rebase manually: git fetch upstream master && git rebase upstream/master.

[github-actions]

🤖 Auto-rebase failed: This branch has conflicts with master that cannot be resolved automatically. Conflicting files: packages/bot/core/src/index.ts. Please rebase manually: git fetch upstream master && git rebase upstream/master.

[github-actions]

🤖 Auto-rebase failed: This branch has conflicts with master that cannot be resolved automatically. Conflicting files: packages/bot/core/src/index.ts. Please rebase manually: git fetch upstream master && git rebase upstream/master.