refactor(procest): $termijnService -> $deadlineService

[rubenvdlinde]

What

Renames the injected dependency's property/parameter name across 15 files, so it matches the DeadlineService type it has held since #808. Includes DeadlineController's shorter $termijn, which is the same dependency under a different name.

Stacked on #808. Merge order: #797 → #803 → #804 → #806 → #807 → #808 → this.

The mistake this commit made first, because it generalises

Renaming a promoted constructor property needs two patterns, not one:

$termijnService          the parameter / promoted declaration
$this->termijnService    every access

A search for $termijnService finds only the first. In a property access the $ sigil belongs to $this, not to the member name — so ->termijnService is a different token and doesn't match.

The first pass renamed all 15 declarations and none of the 47 accesses, leaving every class calling a property that no longer existed.

That isn't a subtle failure — phpunit went from 1777 passing to 20 errors and 3 failures immediately. But it's only loud because a suite covers this code. The same edit in a thinly-tested file would have produced a property-access error on a path nobody runs.

The residual grep at the end of this commit therefore matches the bare word termijnService, with no sigil, so it cannot miss either spelling.

What was deliberately left

Two bare $termijn variables remain and are not this dependency:

file	what it actually holds
SubsidieController	an int of weeks, from $body['termijnWeken']
BeschikkingService	the array returned by $this->bezwaarScheduler->computeTermijn()

Both are "termijn" as a period — a different concept from the service. Renaming them belongs with computeTermijn()/termijnWeken, not here. They were read before being skipped, not assumed.

Verification

• php -l clean on all 15 files
• phpunit, whole unit suite: 1777 tests, 6160 assertions, 5 skipped — green, and identical to the pre-change baseline on both counts
• Every touched lib/ file is phpcs CLEAN
• Residual grep for termijnService (unsigilled) across lib/ and tests/ — none