Feat: Activate or create connection via URL parameters

[andy-k-improving]

Issue: Closes #1788

Description:

Allows external applications to deep-link into Graph Explorer with a database connection pre-configured. On page load, URL search parameters are parsed and the user is prompted to either activate an existing matching connection or create a new one.

Example URL

https://localhost/explorer?graphDbUrl=https%3A%2F%2Fg-xxx.us-west-2.neptune-graph.amazonaws.com&queryEngine=openCypher&awsRegion=us-west-2&serviceType=neptune-graph&name=My%20Graph

Supported parameters

Parameter	Required	Default	Description
graphDbUrl	Yes	—	Database endpoint (URL-encoded)
queryEngine	No	gremlin	gremlin, openCypher, or sparql
awsRegion	No	—	AWS region for IAM signing
serviceType	No	—	neptune-db or neptune-graph
name	No	graphDbUrl	Display label for the connection

Behavior

• Match found → dialog shows "Activate Connection"; clicking Connect activates without resetting the graph session
• No match → dialog shows "Create Connection"; clicking Create adds and activates
• Cancel → dismisses dialog, strips URL params, no changes made
• Dedup → deterministic ID prevents duplicates from repeated URL clicks
• URL stripped → params removed via replaceState after user confirms or cancels

Files changed

File	Description
src/core/AppStatusLoader.tsx	Orchestration: parse params at module level, compute match/pending during render, delegate to dialog
src/core/UrlConnectionDialog.tsx	Presentational dialog component
src/core/urlConnectionParams.ts	Pure functions: parseUrlConnectionParams, findMatchingConnection, buildConnectionFromParams
src/core/urlConnectionParams.test.ts	Unit tests (9 cases)

Testing

• Unit tests: URL parsing (missing params, defaults, full params), matching (case-insensitive, engine mismatch, no match), building (IAM on/off, deterministic IDs)
• Manual: new endpoint → Create dialog; existing endpoint → Connect dialog; no params → normal flow

Check List

• I confirm that my contribution is made under the terms of the Apache 2.0 license.
• I have verified pnpm checks passes with no errors.
• I have verified pnpm test passes with no failures.
• I have covered new added functionality with unit tests if necessary.
• I have updated documentation if necessary.

[kmcginnes]

• Match found → dialog shows "Activate Connection"; clicking Connect activates without resetting the graph session

You must reset the graph session when changing connections.

The reason is that any graph currently on the canvas has the potential to be expanded or the data to be refreshed. But if the connection changed, then the data might not exist in the new connection and will most likely break.

So any connection change should always reset everything.

[acarbonetto]

The reason is that any graph currently on the canvas has the potential to be expanded or the data to be refreshed. But if the connection changed, then the data might not exist in the new connection and will most likely break.

I think this means the connection is already active? I'm not really sure why we would need to 'activate it'? I understand the 'match' strategy, but I think we should have a dialog with the following options:

1. [Cancel] - change to [Ignore]?
2. [Add Connection] - this adds the connection, but doesn't reset the graph session or activate it - this option is not available if the connection already exists (is a match)
3. [Connect] - this adds the connection AND resets the graph session to activate it

[kmcginnes]

Good questions — I reworked this quite a bit; it's now #1828, which replaces this PR.

A connection link opens in a new tab/window — there's no way to push params into an already-loaded Graph Explorer tab, so every link starts a fresh session. That removes the "switching could clear a session you care about" concern: there's nothing on the canvas to lose.

That's what simplifies the dialog question:

resolve(link):
  matches the ACTIVE connection   -> do nothing, clean up the URL
  matches an INACTIVE connection  -> switch to it (no prompt)
  matches nothing                 -> open the create form, prefilled but editable
  invalid params                  -> toast + ignore

@acarbonetto — I dropped the 3-option dialog. Switching to a connection you already have needs no prompt (same as clicking it in the connections list), since the session is fresh anyway. The only friction I kept is the create form for an unknown endpoint — the one case where a link introduces something unvetted. No "add but don't activate" mode; a link's whole intent is to connect.

Matching now also considers auth posture (IAM/region/service type), so a link asking for IAM won't silently reuse a plaintext connection to the same URL.

Closing this in favor of #1828.