fix(lsp): identify JSONC documents correctly

[kvnloo]

Tip leaf (fork-only) — CLEAN

Maps to work-order issue #150. Upstream origin anomalyco#49483 (not touched / not promoted).

What: Map .jsonc to the JSONC language ID so LSP opens JSONC documents correctly.

Commit: 0cae990d363314fbc4d043d88dd13c41519dd092
Origin tip SHA: 9759bf8ebf0b

Proof: fail→pass on tip test opens JSONC documents with the JSONC language ID (GREEN 1 / NEG 1 fail plaintext / RESTORE 1).

github_writes_origin: 0. Codex promote parked.

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[github-actions]

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[kvnloo]

READY_UPSTREAM

Rechecked before promotion:

• upstream PR fix(lsp): identify JSONC documents correctly anomalyco/opencode#49483 is still open
• upstream head is exactly 9759bf8ebf0b3621f4c081b5b5f2c95410383ffc
• no prior kvnloo validation comment is present
• this fork leaf's fail → pass → restore evidence therefore still applies to the exact upstream head

GitHub App cannot write to anomalyco/opencode from this environment (403). Hermes/local-gh may post the evidence comment from this fork PR. Do not open a duplicate PR.