chore: remove LLM module + all dependent surfaces (#135)

Wholesale removal of the LLM integration layer. ~14,200 LOC deleted
across backend and frontend. All chat-driven UIs go with it.

## Backend
- Delete `src/llm/` (7,400 LOC): claude/groq clients, contract_tools,
  contract_evaluator, discuss_tools, mesh_tools, phase_guidance,
  task_output, templates, markdown round-trip, tools, transcript_analyzer.
- Delete handlers wholly dependent on LLM:
  - `chat.rs` (file-level LLM chat at /files/{id}/chat)
  - `mesh_chat.rs` (mesh & task LLM chat + history)
  - `templates.rs` (/contract-types listing)
- Strip LLM uses from `mesh_daemon.rs`:
  - `compute_action_directive` (used phase_guidance::check_deliverables_met
    to nudge supervisors with "all tasks done" messages). The auto-PR
    path below still fires when all tasks finish, so no behaviour lost.
  - `crate::llm::markdown_to_body` → inline 1-line replacement that
    wraps markdown content in a single BodyElement::Markdown. The
    editor re-parses on display, so round-trip is preserved.
- Drop routes: /files/{id}/chat, /mesh/chat, /mesh/chat/history,
  /mesh/tasks/{id}/chat, /contract-types.
- Drop the matching openapi registrations.

## Frontend
- Delete components that were LLM-only:
  - `mesh/UnifiedMeshChatInput.tsx`
  - `listen/DiscussContractModal.tsx`
  - `listen/TranscriptAnalysisPanel.tsx`
  - `listen/ContractPickerModal.tsx`
  - `files/CliInput.tsx`
- Delete the entire /listen page (its primary value-add was
  voice → LLM analysis → contract creation; without LLM the page is
  just a transcript display with no obvious user purpose).
- Delete `hooks/useMeshChatHistory.ts` and `lib/listenApi.ts`
  (transcript-analysis API client to the already-Phase-5-removed
  listen handlers).
- Strip api.ts of LLM exports: LlmModel, ChatMessage/Request/Response,
  UserQuestion/Answer, chatWithFile, MeshChat* types & functions,
  getMeshChatHistory, clearMeshChatHistory, chatWithMeshContext,
  ContractTypeTemplate, listContractTypes, chatWithContract,
  getContractChatHistory, clearContractChatHistory, discussContract,
  PhaseDefinition, DeliverableDefinition.
- mesh.tsx: drop UnifiedMeshChatInput render + the chatContext memo +
  handleTaskUpdatedFromCli (only consumer was the input).
- files.tsx: drop CliInput render + handleGenerateFromElement +
  handleBodyUpdate + handleClearFocus + suggestedPrompt state (all
  CliInput-only).
- NavStrip: drop the /listen link.
- main.tsx: drop the /listen route.

## Net diff: 37 files changed, 58 insertions, 14,281 deletions.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

0 files changed, 0 insertions, 0 deletions