fix(trade): label GMX fallback candles as "GMX Oracle Reference"

[Mohit0628]

What changed and why

fetchOracleCandles in apps/web/src/features/trade/lib/oracle.ts falls back to the GMX API (ENV.ORACLE_URL) but labelled the resulting series "SO4 Oracle Reference". Now that the third-party SO4 oracle worker has been removed, that label misattributes third-party GMX (Arbitrum) prices to SO4. This renames all three GMX-path return sites to "GMX Oracle Reference":

• the aborted-signal early return,
• the successful return's venueName,
• the catch fallback.

No logic, types, or pricing maths changed — it is a display-label correction. The source: "gmx" value was already correct.

A changelog entry is included at .changelog/unreleased/978-gmx-oracle-label.md (type: fixed, area: trade).

Verification

Full gate run locally (Windows), from the repo root:

• bun install --frozen-lockfile
• bun run check:tokens
• bun run check:content
• bun run test
• bun run test:coverage
• bun run build
• bun lint — fails on 9 pre-existing errors (see comment below)
• bun typecheck — fails on 2 pre-existing errors (see comment below)

The two failing checks fail only on errors in files this PR does not modify; the full list is in the comment below. Everything else is green.

Linked issue

Closes #830

[vercel]

@Mohit0628 is attempting to deploy a commit to the Ijai's projects Team on Vercel.

A member of the Team first needs to authorize it.

[Mohit0628]

Quality gate run locally (Windows) — full results

Ran the entire gate from the repo root on fix/830-gmx-oracle-label:

• ✅ bun install --frozen-lockfile
• ✅ bun run check:tokens
• ✅ bun run check:content
• ✅ bun run test
• ✅ bun run test:coverage
• ✅ bun run build
• ❌ bun lint — 9 errors
• ❌ bun typecheck — 2 errors

The two failures are pre-existing and in files this PR does not touch. This change edits three string literals in apps/web/src/features/trade/lib/oracle.ts and adds one changelog entry — it cannot introduce these. Per AGENTS.md ("a red gate is never unrelated"), flagging them explicitly rather than fixing unrelated code inside this PR:

bun lint (9 errors)

• apps/web/src/features/trade/components/chart/TVChartContainer.tsx:20 — import/order
• apps/web/src/features/trade/components/orderbook/DepthLadder.tsx:5 — import/order
• apps/web/src/features/trade/components/orderbook/DepthLadder.tsx:6 — import/order
• apps/web/src/features/trade/components/orderbook/DepthLadder.tsx:221 — @typescript-eslint/no-unnecessary-condition
• apps/web/src/features/trade/components/orderbook/DepthLadder.tsx:222 — @typescript-eslint/no-unnecessary-condition
• apps/web/src/features/trade/components/trade-panel/ConfirmationDialog.tsx:1 — sort-imports
• apps/web/src/features/trade/components/trade-panel/ConfirmationDialog.tsx:135 — @typescript-eslint/no-unnecessary-condition
• apps/web/src/features/trade/components/trade-panel/ConfirmationDialog.tsx:136 — @typescript-eslint/no-unnecessary-condition
• apps/web/src/features/trade/hooks/useSourceFreshness.test.ts:152 — @typescript-eslint/no-unnecessary-type-assertion

bun typecheck (2 errors)

• apps/web/src/features/trade/components/orderbook/DepthLadder.tsx:165 — TS6133: 'midPrice' is declared but its value is never read
• apps/web/src/features/trade/components/trade-panel/ConfirmationDialog.tsx:333 — TS2304: Cannot find name 'ENV'

Happy to open a separate PR for these if that's useful — keeping this one scoped to the label fix.

[Mohit0628]

Disclosure: this contribution was made with the help of Sarvam.ai assistant, it helped the find the issue after which codes and tests were run full gate locally myself.