show model name in footer, drop pullfrog.com link (#484)

* show model name in footer, drop pullfrog.com link

add model slug to buildPullfrogFooter so every Pullfrog comment
displays the active model (e.g. "Using `Big Pickle` (free)" or
"Using `Claude Opus`"). remove the pullfrog.com link from all footers.

Made-with: Cursor

* reject <br/> tags in comment bodies, add prompt guidance

add runtime validation in addFooter that throws if <br/> is followed
by a non-blank line (breaks GitHub heading rendering). the agent sees
the error and retries with clean markdown. also update Summarize mode
prompt to explicitly forbid <br/> tags.

Made-with: Cursor

* fix <br/> guidance: move to event instructions, clarify blank line rule

the formatting rule belongs in DEFAULT_PR_SUMMARY_INSTRUCTIONS (event
instructions), not the Summarize mode prompt. clarify that <br/> must
always be followed by a blank line before headings.

Made-with: Cursor

* generalize block-level HTML rule in summary instructions

add a prominent top-level rule about requiring blank lines between ALL
block-level HTML elements and markdown syntax, not just <br/>.

Made-with: Cursor

* move model to toolState instead of threading through params

model is set once at startup and read everywhere — it belongs on
toolState, not threaded as a separate param through 8 call sites.
postCleanup runs without toolState so it just omits the model label.

Made-with: Cursor

* update models.dev snapshot (openai latest changed)

Made-with: Cursor

* add comment to models snapshot test explaining its purpose

Made-with: Cursor

utils/errorReport.ts

@@ -36,6 +36,7 @@ export async function reportErrorToComment(ctx: ReportErrorParams): Promise<void
     triggeredBy: true,
     workflowRun: runId ? { owner: repoContext.owner, repo: repoContext.name, runId } : undefined,
     customParts,
+    model: ctx.toolState.model,
   });
 
   await octokit.rest.issues.updateComment({