fix(vertexai): pass GenerativeModel's BaseParams to ChatSession

[dlarocque]

startChat wasn't passing GenerativeModel's BaseParams to ChatSession.
So, if a model had a generationConfig, it would never be passed to ChatSession.

This is how the other SDKs behave.

[changeset-bot]

🦋 Changeset detected

Latest commit: 8801ee3

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@firebase/vertexai	Patch
firebase	Patch

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Click here if you're a maintainer who wants to add another changeset to this PR

[google-oss-bot]

Size Report ¹

Affected Products

• @firebase/vertexai

  Type	Base (9952dbc)	Merge (f2829cf)	Diff
  browser	34.7 kB	34.8 kB	+74 B (+0.2%)
  main	35.7 kB	35.8 kB	+74 B (+0.2%)
  module	34.7 kB	34.8 kB	+74 B (+0.2%)

• firebase

  Type	Base (9952dbc)	Merge (f2829cf)	Diff
  firebase-vertexai.js	28.3 kB	28.3 kB	+74 B (+0.3%)

Test Logs

• Base (9952dbc): https://github.com/firebase/firebase-js-sdk/actions/runs/14646189506
• Merge (f2829cf): https://github.com/firebase/firebase-js-sdk/actions/runs/14647921282

1. https://storage.googleapis.com/firebase-sdk-metric-reports/PEE31BlUmz.html

[google-oss-bot]

Size Analysis Report ¹

Affected Products

• @firebase/vertexai

  • GenerativeModel

    Size

    Type	Base (9952dbc)	Merge (f2829cf)	Diff
    size	18.9 kB	19.0 kB	+74 B (+0.4%)
    size-with-ext-deps	37.9 kB	38.0 kB	+74 B (+0.2%)

  • getGenerativeModel

    Size

    Type	Base (9952dbc)	Merge (f2829cf)	Diff
    size	19.1 kB	19.1 kB	+74 B (+0.4%)
    size-with-ext-deps	38.1 kB	38.1 kB	+74 B (+0.2%)

Test Logs

• Base (9952dbc): https://github.com/firebase/firebase-js-sdk/actions/runs/14646189506
• Merge (f2829cf): https://github.com/firebase/firebase-js-sdk/actions/runs/14647921282

1. https://storage.googleapis.com/firebase-sdk-metric-reports/V7p7MQQ5EK.html