Cornerstones-client

- Added stock research fast-path/client parity for transcripts, analyst estimates, ratings, price targets, ratios, key metrics, and research context.

- Added client parity for SEC EDGAR public-data surfaces:
- `stocks filings --provider sec` for official SEC company filings.
- `stocks facts` for compact official SEC company facts.
- Added import-cheap fast-path mappings, tests, and docs for the new stock SEC endpoints.

- Added client parity for Core FX support surfaces:
- `fx options-proxy` for support-only ETF options proxy evidence.
- `fx positioning` for explicit FX positioning provider-availability contracts.
- Added import-cheap fast-path mappings, tests, and docs for the new FX endpoints.

- Aligned public CLI access with Core API policy: basic market data reads no longer require a stored API key.
- Stopped treating browser trial tokens as issued API keys for protected surfaces such as `verify`/`/v1/status`.
- Kept changelog on issued-key auth so admin-only Core policy is not bypassed by local trial fallback.

- Hardened options chain/wall/analysis client parity for Core option truth envelopes: `sec_type=OPT`, `underlying_type`, quote/Greeks/liquidity quality metadata, and read-only safety wording in CLI help/docs.
- Added public aliases for options flags: `--expiration`/`--expiration-date` and `--threshold`/`--threshold-percentile`.
- Kept client options surfaces non-execution-only: no BAG/ComboLeg construction, what-if, order submit/cancel, risk, or reconciliation.

- Let stored browser-trial tokens authenticate GET-based market reads, so `trial token` can be followed by basic quote/read commands without a paid API key.
- Kept trial reads on the Free plan boundary; Pro and Max surfaces still return structured plan-gate errors.
- Sanitized public CLI and fast-path output so upstream vendor/provider labels are normalized before display.
- Updated chart docs/examples for Core `cornerstones_chart_renderer` output and chart bundle artifact semantics.
- Kept client thin: no renderer logic added; chart commands still call Core API and return artifact metadata/URLs.