Add Google OAuth login option and update documentation

[cycomachead]

Add Google OAuth as a secondary login option

Adds Google OAuth as an optional sign-in alternative alongside Canvas. Google login only authenticates existing users matched by email — it never creates new accounts. When Google credentials are not configured, the login flow is unchanged.

Changes

Auth flow

• New /login/canvas/ and /login/google/ routes; /login/ now shows a provider chooser when Google is enabled, otherwise falls back to Canvas directly
• Google callback validates email verification, optional hosted-domain restrictions, and rejects unknown emails with a clear error message
• On first successful Google sign-in, the stable Google subject ID (sub) is stored so subsequent logins aren't dependent on email matching alone

Model

• Added nullable email and google_id columns to User; Canvas login now populates email on create/update

Configuration

• GOOGLE_CLIENT_ID, GOOGLE_CLIENT_SECRET, GOOGLE_HOSTED_DOMAINS env vars (all optional); added to config.py and .env.sample
• Google OAuth provider is only registered when credentials are present

Templates

• New login.html.j2 login chooser shown when Google is enabled

Docs

• New docs/google-oauth.md with step-by-step Google Cloud Console setup (consent screen, OAuth client, redirect URIs, JS origins), env var reference, matching logic explanation, and troubleshooting table
• README.md updated with an Authentication section linking to the doc

Tests

• 8 new unit tests covering: login chooser rendering, Google redirect, successful callback, unknown email rejection, hosted-domain enforcement, and unverified email rejection

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Superconductor Ticket Implementation | Guided Review

[github-actions]

Coverage for unit tests for Python 3.10

File	Stmts	Miss	Cover	Missing
server
__init__.py	50	4	92%	21–22, 67, 75
cache.py	6	1	83%	12
forms.py	122	15	88%	23–25, 41–43, 68–70, 149–152, 159, 167
models.py	169	35	79%	58, 62, 65, 68, 71, 74–79, 109, 112–121, 124, 127, 153, 165, 169, 173, 177–178, 184, 187, 207, 210, 231, 234, 248
views.py	692	591	15%	35, 45–81, 91–125, 136–140, 157–166, 182–199, 210–217, 226–248, 259–272, 281, 292–295, 306–325, 338–362, 371–393, 402–429, 438–447, 456–498, 509–514, 522–526, 535–565, 574–604, 613–646, 655–685, 694–711, 718, 723–727, 736–782, 788–839, 845–855, 860–880, 885–910, 915–930, 935–954, 959–960, 965–978, 992, 997, 1005–1006
server/controllers
__init__.py	82	46	44%	26–44, 47–49, 60–87, 90, 101–110, 113
auth_controllers.py	108	36	67%	24, 37–39, 44–75, 90, 95–96, 132–133, 143–144, 172–174
dev_login_controllers.py	34	23	32%	11–25, 30–39, 44–56
health_controllers.py	20	7	65%	17–18, 23–27
server/services/auth
__init__.py	39	11	72%	22, 51, 60–76, 80, 85–86, 91–92
server/services/canvas
__init__.py	80	61	24%	18–25, 29, 33, 37, 43, 55–64, 69–105, 109–124, 128
fake_canvas.py	39	26	33%	9, 12, 15, 20–25, 28–29, 37–46, 49–56
server/services/core
assign.py	65	3	95%	25, 28, 92
data.py	54	37	31%	12–17, 21–25, 29–33, 37–39, 43–54, 58, 69–71, 75–76, 80–81, 85–86
export.py	27	22	19%	11–44
room.py	61	56	8%	11–33, 41–89
student.py	116	5	96%	29, 33–34, 43, 150
server/services/csv
__init__.py	20	13	35%	11–12, 19, 26–29, 36–41
server/services/email
__init__.py	41	31	24%	19–36, 40–72
smtp.py	92	31	66%	18, 29–31, 33–35, 49–51, 68–76, 88–89, 101–108, 112–114, 125–126
server/services/email/templates
__init__.py	33	1	97%	20
server/services/google
__init__.py	54	29	46%	23, 31, 33, 41–44, 48–54, 58–77
server/typings
exception.py	34	6	82%	42, 53, 59–60, 69, 72
server/utils
date.py	7	1	86%	30
misc.py	16	13	19%	5–9, 13–19, 23
TOTAL	2100	1104	47%

Tests	Skipped	Failures	Errors	Time
74	0 💤	0 ❌	0 🔥	10.938s ⏱️

[github-actions]

Coverage for unit tests for Python 3.11

File	Stmts	Miss	Cover	Missing
server
__init__.py	50	4	92%	21–22, 67, 75
cache.py	6	1	83%	12
forms.py	122	15	88%	23–25, 41–43, 68–70, 149–152, 159, 167
models.py	169	35	79%	58, 62, 65, 68, 71, 74–79, 109, 112–121, 124, 127, 153, 165, 169, 173, 177–178, 184, 187, 207, 210, 231, 234, 248
views.py	692	591	15%	35, 45–81, 91–125, 136–140, 157–166, 182–199, 210–217, 226–248, 259–272, 281, 292–295, 306–325, 338–362, 371–393, 402–429, 438–447, 456–498, 509–514, 522–526, 535–565, 574–604, 613–646, 655–685, 694–711, 718, 723–727, 736–782, 788–839, 845–855, 860–880, 885–910, 915–930, 935–954, 959–960, 965–978, 992, 997, 1005–1006
server/controllers
__init__.py	82	46	44%	26–44, 47–49, 60–87, 90, 101–110, 113
auth_controllers.py	108	36	67%	24, 37–39, 44–75, 90, 95–96, 132–133, 143–144, 172–174
dev_login_controllers.py	34	23	32%	11–25, 30–39, 44–56
health_controllers.py	20	7	65%	17–18, 23–27
server/services/auth
__init__.py	39	11	72%	22, 51, 60–76, 80, 85–86, 91–92
server/services/canvas
__init__.py	80	61	24%	18–25, 29, 33, 37, 43, 55–64, 69–105, 109–124, 128
fake_canvas.py	39	26	33%	9, 12, 15, 20–25, 28–29, 37–46, 49–56
server/services/core
assign.py	65	3	95%	25, 28, 92
data.py	54	37	31%	12–17, 21–25, 29–33, 37–39, 43–54, 58, 69–71, 75–76, 80–81, 85–86
export.py	27	22	19%	11–44
room.py	61	56	8%	11–33, 41–89
student.py	116	5	96%	29, 33–34, 43, 150
server/services/csv
__init__.py	20	13	35%	11–12, 19, 26–29, 36–41
server/services/email
__init__.py	41	31	24%	19–36, 40–72
smtp.py	92	31	66%	18, 29–31, 33–35, 49–51, 68–76, 88–89, 101–108, 112–114, 125–126
server/services/email/templates
__init__.py	33	1	97%	20
server/services/google
__init__.py	54	29	46%	23, 31, 33, 41–44, 48–54, 58–77
server/typings
exception.py	34	6	82%	42, 53, 59–60, 69, 72
server/utils
date.py	7	1	86%	30
misc.py	16	13	19%	5–9, 13–19, 23
TOTAL	2100	1104	47%

Tests	Skipped	Failures	Errors	Time
74	0 💤	0 ❌	0 🔥	10.029s ⏱️

[codecov]

Codecov Report

❌ Patch coverage is 78.82353% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 47.42%. Comparing base (4b805f6) to head (16ae9e2).

Files with missing lines	Patch %	Lines
server/controllers/auth_controllers.py	82.19%	13 Missing ⚠️
server/services/auth/__init__.py	50.00%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #89      +/-   ##
==========================================
+ Coverage   46.08%   47.42%   +1.34%     
==========================================
  Files          28       28              
  Lines        2018     2100      +82     
==========================================
+ Hits          930      996      +66     
- Misses       1088     1104      +16     

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