workflow: add bug Gitea label + tag 6 existing bugs

New label for observable misbehaviour distinct from
additive-feature work and clean-up tasks. The /boss pickup
order treats a bug differently from a feature (a bug typically
gets RED-first TDD via skills/debug, a feature goes through
brainstorm), so the label earns its keep.

Tagged in Gitea (6 of 24 issues):

- #7  io/print_float always-emit-.0
       (surface vs runtime printer inconsistent)
- #9  ailang-plan-recon site-undercount
       (tool under-counted 4× across two milestones)
- #10 design_schema_drift.rs fidelity widening
       (test produces false negatives on §"Data model" gaps)
- #12 Zero-arg `(app f)` rejected at parse
       (parser disagrees with the AST schema)
- #15 *.bump_s throughput baseline stale
       (bench false-positive on environmental drift)
- #16 check.py RC-latency *.max_us
       (bench false-positive: 3-of-3 null changes)

Borderline cases left unlabelled (diagnostic usability,
load_workspace limitation, dormant constraint-drop, advisory
Sweep-5 wart) — they aren't observable wrong behaviour, just
suboptimal.

In-tree changes:

- CLAUDE.md: Gitea-issues bullet adds `bug` to the label set
  with the same description string Gitea carries.
- skills/boss/SKILL.md: Step 1 filter snippet includes `bug`.
- skills/brainstorm/SKILL.md: Step 7.5 tea-create template
  --labels choice set includes `bug`.

Distribution after tagging: 3 feature + 6 bug + 5 idea + 10
unlabelled = 24 open issues. Verification: cargo test
--workspace 647/0/2, architect_sweeps exit 0.

CLAUDE.md

@@ -227,10 +227,11 @@ not retroactively renamed.
   milestones, features, todos, and ideas. Browse:
   http://192.168.178.103:3000/Brummel/AILang/issues. CLI: `tea
   issues ls --repo Brummel/AILang`. Labels: `feature`
-  (substantive addition, no full spec), `idea` (may be cut, no
-  commitment), `in-progress` (work has started). An unlabelled
-  issue is the default: a concrete task to just do, no spec
-  needed. Big chunks live as Gitea **milestone containers**
+  (substantive addition, no full spec), `bug` (observable
+  misbehaviour — surface inconsistency, false positive, wrong
+  output), `idea` (may be cut, no commitment), `in-progress`
+  (work has started). An unlabelled issue is the default: a
+  concrete task to just do, no spec needed. Big chunks live as Gitea **milestone containers**
   (first-class Gitea concept, not a label — needs a
   `docs/specs/` entry, opening one bounces back to the user in
   /boss); smaller items are standalone issues. No formal