docs: update package README links and deprecate keepSession

[wabicai]

Summary

Point published package READMEs at the 1.2.x Getting Started path, omit the stale iframe connectSrc sample, and mark public keepSession as deprecated.

Intent and context

The developer portal 1.2.0 docs (see #920) tell integrators to:

• Start at /en/hardware-sdk/getting-started
• Omit connectSrc so @onekeyfe/hd-web-sdk fills https://jssdk.onekey.so/<installed-version>/
• Use useEmptyPassphrase / openWalletSession + passphraseState instead of keepSession

npm READMEs and CommonParams still taught the old contract.

Root cause

Package-surface docs were not updated when Hardware SDK 1.2.0 shipped Protocol V2 wallet sessions.

Design decisions

• README links go to https://developer.onekey.so/en/hardware-sdk/getting-started.
• hd-web-sdk init sample omits connectSrc; the SDK default is already DEFAULT_DOMAIN from getSDKVersion().
• @deprecated is on public CommonParams.keepSession only. Transport release(..., keepSession) stays internal.
• getPassphraseState stays compatibility, not deprecated.

Compatibility and risk

No runtime change. Existing keepSession: true calls still work. TypeScript consumers see a deprecation warning.

Hardware coverage

Not applicable.

Test plan

• yarn agent:check --profile commit lint/whitespace/agent-context passed
• @onekeyfe/hd-core test: 1 unrelated failure in evmSignTypedData.test.ts (BigNumber parse of 0x89). This PR only touches README + a JSDoc block on keepSession.
• Staged files reviewed: 10 READMEs + packages/core/src/types/params.ts

[wabicai]

Folded into #920 — README + keepSession deprecation now live on docs/developer-portal-1.2.0.