URI handler (1/3): route-map refactor + deep-link constants

[amitjoshi438]

PR 1 of 3 — Phase 0–1 foundation for the Power Pages → VS Code "create" deep links. Behavior-preserving refactor; no user-facing change.

Why

We're adding two new deep links launched from the Power Pages home page that open VS Code into a create experience:

• vscode://…/agenticCreate — agentic flow (terminal CLI agent host carrying the Power Pages plugin)
• vscode://…/pacCreate — PAC CLI flow

Before wiring any of that behavior, this PR lays the routing + contract foundation so the follow-ups stay small and reviewable. Everything in the full effort ships dark (ECS-gated, off by default); this PR alone changes no behavior at all.

What changed

• uriHandler/uriHandler.ts — replaced the handleUri if/else chain with a ReadonlyMap<string, UriRouteHandler> route table built in the constructor and dispatched by uri.path. Unknown paths are a no-op (forward-compatible). Exported the UriHandler class so it's unit-addressable. /open and /pcfInit dispatch to the exact same code as before.
• uriHandler/constants/uriConstants.ts — added the versioned, secret-free deep-link contract: new paths (/agenticCreate, /pacCreate), params (region, tenantid, source, agenthost, v), value/version constants (SOURCE_VALUES, AGENT_HOST_VALUES, CONTRACT_VERSION), and the matching UriPath enum members. No handlers consume the new paths yet.

Tests

• test/unit/uriConstants.test.ts (new) — pure/no-vscode unit coverage of the contract constants.
• test/integration/uriHandler.test.ts (new) — asserts /open and /pcfInit still route to their handlers and unknown paths are ignored.

Design notes

• The vscode:// URL is treated as a versioned contract (v=1) so the Power Pages home page and the extension can evolve independently.
• Route-map dispatch makes adding a path a one-line registration (used by PRs 2–3) instead of growing a conditional.

Validation

gulp lint clean · compile-tests clean · npm test 106 passing · npm run build OK.

Risk / rollout

Effectively zero: no new path is wired to behavior in this PR, and the two existing paths are dispatched identically. New paths become active only in PR 3, behind ECS gates that default off.

Stack (merge in order)

1. this PR (URI handler (1/3): route-map refactor + deep-link constants #1625) → main — router refactor + deep-link constants
2. URI handler (2/3): extract shared auth/environment service #1626 → auth/environment service extraction
3. URI handler (3/3): dark gated create deep-link handlers #1627 → dark, ECS-gated create handlers + telemetry

Branches are pushed from the fork amitjoshi438/powerplatform-vscode; since intermediate branches can't be pushed upstream, #1626/#1627 target main and show cumulative diffs until earlier PRs merge (each body names its focus commit). They auto-rebase to a clean single-commit diff and flip to ready once the preceding PR merges.

Co-authored-by: Copilot App 223556219+Copilot@users.noreply.github.com

[amitjoshi438]

Superseded: re-raised directly against the base repo (no fork) so CI secrets are available and the stack has proper isolated per-PR diffs. Replaced by #1628 / #1629 / #1630.