feat: OpenAI, Anthropic, and native-Ollama providers + media pipeline

Phase 3:
- provider/openai: Chat Completions for OpenAI + compat endpoints (SSE
  streaming with by-index tool-call assembly, response_format json_schema,
  legacy max_tokens option, reasoning_effort)
- provider/anthropic: Messages API (tool_use/tool_result, GA structured
  output via output_config.format, full SSE event parser, 529 transient)
- provider/ollama: one native /api/chat client behind the ollama,
  ollama-cloud, and foreman built-ins (presets; NDJSON streaming tolerant
  of foreman's buffered single-object responses; object tool arguments;
  format-schema structured output; think mapping)
- media/: capability normalization (sniff, downscale, transcode, byte
  ladder, ErrUnsupported), wired into the chain executor per target with
  penalty-free advance past incapable elements
- registry: real provider + scheme wiring, WithHTTPClient option, required
  env-foreman TLS chat round-trip test
- ADR-0009 multimodal strategy, ADR-0010 tools/structured mapping; README
  matrix + CLAUDE.md synced

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

progress.md

@@ -1,5 +1,45 @@
 # progress
 
+## 2026-06-10 — Phase 3: REST providers (OpenAI, Anthropic, Ollama×3) + media
+
+**Landed:**
+- `provider/openai`: Chat Completions client for OpenAI and every
+  OpenAI-compatible endpoint (tools with string-arguments mapping, strict
+  SSE streaming incl. by-index tool-call assembly and the empty-choices
+  usage chunk, response_format json_schema, max_completion_tokens with a
+  WithLegacyMaxTokens compat option, reasoning_effort).
+- `provider/anthropic`: Messages API client (anthropic-version 2023-06-01,
+  required-max_tokens defaulting, tool_use/tool_result blocks with native
+  is_error, GA structured output via output_config.format, full SSE event
+  parser with input_json_delta buffering, 529-overloaded classified
+  transient, usage sums cache tokens).
+- `provider/ollama`: ONE native /api/chat client serving ollama (local,
+  OLLAMA_HOST normalization), ollama-cloud (https://ollama.com + bearer
+  OLLAMA_API_KEY), and foreman (base URL + bearer; tolerates its
+  buffered-single-object "streaming"). Object tool arguments, tool_name
+  results, format-schema structured output, think-level mapping, NDJSON
+  streaming with 16MB lines.
+- `media/`: normalization pipeline per ADR-0009 (magic-byte sniffing,
+  box-filter downscale, transcode preference ladder, byte-budget quality
+  ladder, webp passthrough-or-reject, copy-on-write, everything-unfittable
+  wraps ErrUnsupported).
+- Chain executor now normalizes media PER TARGET before each attempt and
+  advances penalty-free past targets that can't take the request (proven:
+  text-only head + vision fallback; per-target downscale assertions).
+- Registry: real providers + scheme factories wired for openai, anthropic,
+  ollama, ollama-cloud, foreman (google still stubbed, Phase 4);
+  WithHTTPClient registry option; required env-foreman TLS chat round-trip
+  test (LLM_FM=foreman://token@host → Parse("fm/qwen3:30b") → bearer
+  arrives, chat answers).
+- ADR-0009 (multimodal), ADR-0010 (tools/structured mapping); README
+  matrix flipped to ✅ for the four landed provider families; ~70 new
+  hermetic tests across the three provider packages + media.
+- Run note: openai/anthropic/media were built by three parallel
+  subagents against the frozen llm contract; ollama/foreman, chain wiring,
+  and registry integration done in the main line. All gates green.
+
+**Next:** Phase 4 — Google provider on google.golang.org/genai.
+
 ## 2026-06-10 — Phase 2: health + failover chain, proven
 
 **Landed:** the full deterministic failover test matrix over the fake