Fix Expected VAR_SIGN error when resolving PR review threads

[mrbiggred]

Sometimes an Expected VAR_SIGN, actual: UNKNOWN_CHAR error is raised when resolving a review conversation with the smp-apply-github-pr-feedback skill. The error happens when the GraphQL query declares variables (e.g. mutation($threadId: ID!) with -f threadId=...) and the $ characters get mangled by shell quoting.

This change strengthens the existing inline-values guidance in two ways:

• references/graphql-queries.md now names the Expected VAR_SIGN error and explains why variable declarations trigger it, so the guidance is grounded rather than an unexplained rule.
• The skill's Error Handling section now includes a recovery path: if a GraphQL call fails with this error, rewrite the query with inline values instead of retrying the same command (the failure transcript in the issue shows the same broken command being retried verbatim).

Closes #10

[Copilot]

Pull request overview

Updates the smp-apply-github-pr-feedback skill documentation to better diagnose and recover from a GitHub GraphQL parsing failure (Expected VAR_SIGN, actual: UNKNOWN_CHAR) that can occur when shell quoting mangles $ in GraphQL variable declarations.

Changes:

• Adds explicit error recognition + recovery guidance to the skill’s Error Handling section (rewrite to inline GraphQL values instead of retrying a variables-based query).
• Expands references/graphql-queries.md to name the error, explain the root cause (shell quoting affecting $), and reinforce the “inline values only” rule with concrete examples.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
plugins/smp-github/skills/smp-apply-github-pr-feedback/SKILL.md	Adds a concrete recovery path when GraphQL calls fail with the VAR_SIGN parsing error.
plugins/smp-github/skills/smp-apply-github-pr-feedback/references/graphql-queries.md	Strengthens inline-values guidance by naming the error and explaining why variable declarations can trigger it.

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