Add Discord-native hybrid front-end for Jarvis (bot + bridge)

Transform isair/jarvis into a Discord-controlled voice assistant running on
the Ubuntu VNC desktop, keeping the mature ~39k-line Python brain intact.

- bot/ (Node + bun, discord.js): /자비스 slash commands (ephemeral),
  voice channel join + voice receive/playback, pluggable VNC screen broadcast
  (selfbot live / noVNC / screenshot)
- bridge/ (Python, Flask): wraps jarvis STT + run_reply_engine + Piper TTS
  behind a thin localhost HTTP API
- .env.example, scripts/ (start_bridge/start_bot/dev), README rewrite,
  docs/language-comparison.md and docs/vnc-xfce-setup.md

Language decision: hybrid (Python brain + Node/bun Discord layer) because
Discord blocks bot video; native screen broadcast only works via a Node
selfbot library.

tests/performance/README.md

@@ -0,0 +1,43 @@
+# Performance tests
+
+Per-context timings for the reply pipeline. Excluded from the default pytest run
+(see `pytest.ini`'s `addopts = -m "not performance"`).
+
+## Running
+
+```bash
+pytest tests/performance/ -v -m performance -s
+```
+
+The `-s` flag lets the report table print to stdout. Tests auto-skip when Ollama
+is unreachable, so the harness is safe to leave in the repo.
+
+## Env vars
+
+| Var | Default | Description |
+|-----|---------|-------------|
+| `JARVIS_PERF_OLLAMA_URL` | `http://localhost:11434` | Ollama endpoint |
+| `JARVIS_PERF_MODEL` | `gemma4:e2b` | Model pulled in Ollama for the run |
+| `JARVIS_PERF_RUNS` | `3` | Runs per query (bump for tighter p95) |
+| `JARVIS_PERF_REPORT_DIR` | `tests/performance/reports/` | JSON report output |
+
+`PERF_RUNS=3` is a fast-iteration default. For stable p95 numbers when
+benchmarking a change, use `JARVIS_PERF_RUNS=10` or higher.
+
+## What it measures
+
+- **`test_micro_benchmark_tiny_prompt`** — one warmup + N tiny round-trips.
+  Hardware baseline: the floor for every context's per-call cost.
+- **`test_pipeline_timings_by_context`** — three representative queries × N runs
+  of `run_reply_engine`, with per-context timings bucketed via stack-frame
+  inspection in [`timing_recorder.py`](timing_recorder.py).
+
+Shape invariants (not absolute numbers):
+- Evaluator p50 ≤ main chat turn p50 × 1.5.
+- Tool router p50 ≤ main chat turn p50 × 1.5.
+- Enrichment extractor shares the router model chain.
+
+Unmapped callers print as `other:<qualname>` — that's a signal to update the
+`_CALLER_TO_CONTEXT` map in `timing_recorder.py` alongside `docs/llm_contexts.md`.
+
+Reports are written to `reports/` and git-ignored.