chore(release): prepare 0.61.0 GFQL release notes

[lmeyerov]

Summary

• Replaces the stale 0.60.1 notes with a concrete 0.61.0 candidate while preserving the [Development] changelog heading until release finalization.
• Minor version is appropriate because fix(gfql): require explicit epoch-ms comparisons #2197 adds the additive DateTimeValue.from_epoch API and typed-wire unit form, alongside additive index APIs and Cypher syntax.
• Consolidates candidate notes for perf(gfql): add explicit relationship-type adjacency sidecars #2184, feat(gfql): add typed node segment indexes for indexed hops #2192/perf(gfql): lower simple destination node filters into indexed hops #2193, fix(gfql): require explicit epoch-ms comparisons #2197, feat(gfql): support Cypher backtick identifiers #2198, fix(gfql): distinguish Call execution errors #2199, and fix(gfql): support cuDF index byte reporting #2201.
• Keeps temporal wording scoped: bare numeric/datetime comparisons are rejected in GFQL comparison predicates and typed wire inputs; this does not alter all mixed-type Cypher equality semantics.
• Keeps publication, tagging, release deployment, and MCP deployment separately gated.

Validation

• Base is actual master bfb2ffaa8b548dced973bee6c2d9cc380d3e0d00 (includes fix(gfql): support cuDF index byte reporting #2201).
• Exact-head hosted CI run 39072620896 is SUCCESS; CodeQL run 39072620912 is SUCCESS with zero failures and applicable lanes passing (docs-only paths skipped).
• Exact-head RTD build 35215670 is terminal finished with success=true.
• Landed fix(gfql): support cuDF index byte reporting #2201 cross-engine focused tests: local pandas/Polars 88 passed, 1 skipped; DGX cuDF 26.02.01/CuPy 13.6.0 127 passed, 1 skipped (/tmp/dgx-gfql-receipts/pr2201-master-bfb2ffaa-dgx-v21/); DGX cuDF 25.02.02/CuPy 13.4.0 127 passed, 1 skipped (/tmp/dgx-gfql-receipts/pr2201-master-bfb2ffaa-dgx-v22/).
• Local pandas/Polars MCP acceptance at this proposal head passed: temporal, epoch, empty-match, rejection, quoted-identifier, aggregation, node lifecycle, and E306 coverage. Receipt: plans/gfql-ic4-perf/release-readiness-0.61.0/receipts/local-mcp-pandas-polars-bfb2ffaa8.json.
• Deployed/server MCP acceptance remains separately gated. This proposal changes only CHANGELOG.md.