Raise default agent token budget for reasoning models

The tracker mapping, common-pattern enrichment, and third-party
disambiguation agents default to a small max-tokens budget on the
premise that their final output is tiny structured JSON. On
reasoning models such as the GPT-5 family, reasoning tokens count
against max_tokens, so a small budget is consumed by reasoning and
the JSON is truncated, surfacing as "unexpected end of JSON input".

Raise the defaults to 4096 (1024 -> 4096 for tracker mapping, 512
-> 4096 for disambiguation) to leave headroom for the reasoning
phase. Update the bootstrap builder default, its test, and the
production values example to match.

Signed-off-by: Émile Ré <emile@probo.com>

pkg/thirdparty/disambiguation_agent.go

@@ -44,10 +44,14 @@ const (
 	// provider, not a real budget.
 	defaultDisambiguationTimeout = 45 * time.Second
 
-	// defaultDisambiguationMaxTokens caps the agent's structured
-	// output when the config carries no max-tokens budget. The output
-	// is a single id plus a one-sentence rationale.
-	defaultDisambiguationMaxTokens = 512
+	// defaultDisambiguationMaxTokens caps the agent's output when the
+	// config carries no max-tokens budget. The final output is tiny (a
+	// single id plus a one-sentence rationale), but the budget must
+	// leave ample headroom for reasoning models (e.g. the GPT-5
+	// family): their reasoning tokens count against max_tokens, so too
+	// small a budget gets consumed by reasoning and truncates the JSON,
+	// surfacing as "unexpected end of JSON input".
+	defaultDisambiguationMaxTokens = 4096
 )
 
 // DisambiguationConfig configures the third-party disambiguation