Tag coefficient not applied when multiple tags exist on a task

Given the following configuration:

```ini
data.location=.
hooks.location=./hooks

urgency.uda.tags.foo.coefficient=10
urgency.uda.tags.bar.coefficient=5
```

We can show that the tag coefficient is not applied when more than one tag exists on a task.

To see the problem in action create a `taskrc` file with the above config in an empty directory and run the following commands:

```sh
# Create task with one tag and now additional urgency
$ task rc:taskrc add Test +baz
TASKRC override: taskrc
Created task 1.

# Show list of tasks where urgency is as expected
$ task rc:taskrc
TASKRC override: taskrc

ID Age Tag Description Urg
1 14s baz Test 0.8

1 task

# Add tag bar, expecting the urgency to go up
$ task rc:taskrc 1 modify +bar
Modifying task 1 'Test'.
Modified 1 task.
TASKRC override: taskrc
$ task rc:taskrc
TASKRC override: taskrc

ID Age Tag Description Urg
1 2min bar baz Test 0.9

1 task

# Show task 1 (With non-important part stripped out) - urgency did not go up
$ task rc:taskrc 1
TASKRC override: taskrc

Name Value
ID 1
Urgency 0.9
[tag_bar x]
[tag_baz x]

tags 0.9 * 1 = 0.9
------
0.9

# Remove tag baz, so only one tag with a coefficient is present
$ task rc:taskrc 1 modify -baz
Modifying task 1 'Test'.
Modified 1 task.
TASKRC override: taskrc

# Show task 1 (With non-important part stripped out) - urgency is as expected
$ task rc:taskrc 1
TASKRC override: taskrc

Name Value
ID 1
Urgency 5.8
[tag_bar x]

tags 0.8 * 1 = 0.8
UDA tags.bar 1 * 5 = 5
------
5.8

# Add second tag with coefficient - expecting urgency to be 15+
$ task rc:taskrc 1 modify +foo
Modifying task 1 'Test'.
Modified 1 task.
TASKRC override: taskrc

# Show task 1 (With non-important part stripped out) - urgency is incorrect
$ task rc:taskrc 1
TASKRC override: taskrc

Name Value
ID 1
Description Test
Status Pending
Entered 2024-12-17 13:54:58 (7min)
Last modified 2024-12-17 14:01:53 (21s)
Tags bar foo
Virtual tags LATEST PENDING READY TAGGED UNBLOCKED
UUID 6cac55d8-89da-440d-b8e7-1aa676963fe5
Urgency 0.9
[tag_bar x]
[tag_foo x]

tags 0.9 * 1 = 0.9
------
0.9
```

Output of `task diag`

```
$ task rc:taskrc diag
TASKRC override: taskrc

task 3.1.0
Platform: Darwin

Compiler
Version: Apple LLVM 16.0.0 (clang-1600.0.26.3)
Caps: +stdc +stdc_hosted +LP64 +c8 +i32 +l64 +vp64 +time_t64
Compliance: C++17

Build Features
CMake: 3.30.3
libuuid: libuuid + uuid_unparse_lower
Build type: Release

Configuration
File: taskrc (found), 149 bytes, mode 100644
Data: . (found), dir, mode 40755
GC: Enabled
$EDITOR: hx
Hooks
System: Enabled
Location: ./hooks
(-none-)

Tests
Terminal: 252x75
Broken ref: Scanned 2 tasks for broken references:
No broken references found
```

As a sidenote: My terminal is 170x61 and not 252x75 as seen in the diag output.