AI progress: honest milestone bar from closed JSON contract units

Replace the char-count estimate (EST_OUTPUT_CHARS) with ContractProgress:
points are earned only when real output units complete — first token (5),
each closed contract key / array item (5-90), root closed (95), stored (100).
Reasoning/thinking streams no longer fake progress: the first thinking
delta fires the first-token milestone ('the model is alive') and holds.
Surface the job's tone through ProcessingJobOut/JobInfo so the bar can
label itself 'Summarizing dry wit…'. Test rewritten to pin the new
honest-thinking semantics.

backend/tests/test_ai_adapters.py

@@ -155,10 +155,12 @@ async def test_openai_compat_streams_with_progress():
     assert all(0 <= p <= 99 for p in seen_pcts)  # never claims 100 early
 
 
-async def test_openai_compat_thinking_moves_progress_before_content():
-    """qwen3-on-llama.cpp streams reasoning_content for most of the run;
-    progress must climb during that phase, not sit at "waiting for model"
-    and then jump straight to done."""
+async def test_openai_compat_thinking_earns_only_first_token():
+    """qwen3-on-llama.cpp streams reasoning_content for most of the run.
+    Thinking is real work but NOT contract output: it fires the 5%
+    first-token milestone once ("the model is alive") and then holds.
+    Progress only climbs when JSON contract units actually close — a
+    continuous percent over the thinking span would be a fake estimate."""
     import json as _json
 
     def sse(request: httpx.Request) -> httpx.Response:
@@ -177,10 +179,14 @@ async def test_openai_compat_thinking_moves_progress_before_content():
     seen_pcts = []
     res = await p.summarize("t", on_progress=seen_pcts.append)
     assert res.short == "Done."  # reasoning never enters the reply
-    # The ticker must report real mid-run values while only reasoning
-    # streamed — otherwise the UI shows no percentage for the whole job.
-    assert len(seen_pcts) > 10
-    assert seen_pcts[-1] > 50
+    # Thinking earned exactly one tick: the first-token milestone. No
+    # fake crawl across the reasoning span.
+    assert seen_pcts[0] == 5
+    assert seen_pcts.count(5) == 1
+    assert max(seen_pcts) <= 99  # never claims 100 before storage
+    # Contract units closing does move the bar to the root milestone.
+    assert seen_pcts[-1] == 95
+    assert seen_pcts == sorted(seen_pcts)
 
 
 async def test_openai_compat_partial_json_gets_defaults():